<s>
ATX	B-Architecture
(	O
Advanced	O
Technology	O
eXtended	O
)	O
is	O
a	O
motherboard	B-Device
and	O
power	O
supply	O
configuration	O
specification	O
,	O
patented	O
by	O
David	O
Dent	O
in	O
1995	O
at	O
Intel	O
,	O
to	O
improve	O
on	O
previous	O
de	O
facto	O
standards	O
like	O
the	O
AT	B-Device
design	I-Device
.	O
</s>
<s>
It	O
was	O
the	O
first	O
major	O
change	O
in	O
desktop	B-General_Concept
computer	I-General_Concept
enclosure	I-General_Concept
,	O
motherboard	B-Device
and	O
power	O
supply	O
design	O
in	O
many	O
years	O
,	O
improving	O
standardization	O
and	O
interchangeability	O
of	O
parts	O
.	O
</s>
<s>
The	O
specification	O
defines	O
the	O
dimensions	O
;	O
the	O
mounting	O
points	O
;	O
the	O
I/O	O
panel	O
;	O
and	O
the	O
power	O
and	O
connector	O
interfaces	O
among	O
a	O
computer	B-General_Concept
case	I-General_Concept
,	O
a	O
motherboard	B-Device
,	O
and	O
a	O
power	O
supply	O
.	O
</s>
<s>
ATX	B-Architecture
is	O
the	O
most	O
common	O
motherboard	B-Device
design	O
.	O
</s>
<s>
Other	O
standards	O
for	O
smaller	O
boards	O
(	O
including	O
microATX	B-Device
,	O
FlexATX	B-Device
,	O
nano-ITX	B-Device
,	O
and	O
mini-ITX	B-Architecture
)	O
usually	O
keep	O
the	O
basic	O
rear	O
layout	O
but	O
reduce	O
the	O
size	O
of	O
the	O
board	O
and	O
the	O
number	O
of	O
expansion	O
slots	O
.	O
</s>
<s>
Dimensions	O
of	O
a	O
full-size	O
ATX	B-Architecture
board	O
are	O
,	O
which	O
allows	O
many	O
ATX	B-Architecture
chassis	O
to	O
accept	O
microATX	B-Device
boards	O
.	O
</s>
<s>
The	O
ATX	B-Architecture
specifications	O
were	O
released	O
by	O
Intel	O
in	O
1995	O
and	O
have	O
been	O
revised	O
numerous	O
times	O
since	O
.	O
</s>
<s>
The	O
most	O
recent	O
ATX	B-Architecture
motherboard	I-Architecture
specification	O
is	O
version	O
2.2	O
.	O
</s>
<s>
The	O
most	O
recent	O
ATX12V	O
power	O
supply	O
unit	O
specification	O
is	O
ATX	B-Architecture
3.0	O
released	O
in	O
February	O
2022	O
.	O
</s>
<s>
EATX	O
(	O
Extended	B-Architecture
ATX	I-Architecture
)	O
is	O
a	O
bigger	O
version	O
of	O
the	O
ATX	B-Architecture
motherboard	I-Architecture
with	O
dimensions	O
.	O
</s>
<s>
While	O
some	O
dual	O
CPU	O
socket	O
motherboards	B-Device
have	O
been	O
implemented	O
in	O
ATX	B-Architecture
,	O
the	O
extra	O
size	O
of	O
EATX	O
makes	O
it	O
the	O
typical	O
form	O
factor	O
for	O
dual	O
socket	O
systems	O
,	O
and	O
with	O
sockets	O
that	O
support	O
four	O
or	O
eight	O
memory	O
channels	O
,	O
for	O
single	O
socket	O
systems	O
with	O
a	O
large	O
number	O
of	O
memory	O
slots	O
.	O
</s>
<s>
In	O
2004	O
,	O
Intel	O
,	O
announced	O
by	O
Mason	O
Rametse	O
,	O
the	O
BTX	B-Device
(	O
Balanced	B-Device
Technology	I-Device
eXtended	I-Device
)	O
standard	O
,	O
intended	O
as	O
a	O
replacement	O
for	O
ATX	B-Architecture
.	O
</s>
<s>
While	O
some	O
manufacturers	O
adopted	O
the	O
new	O
standard	O
,	O
Intel	O
discontinued	O
any	O
future	O
development	O
of	O
BTX	B-Device
in	O
2006	O
.	O
,	O
the	O
ATX	B-Architecture
design	O
still	O
remains	O
the	O
de	O
facto	O
standard	O
for	O
personal	O
computers	O
.	O
</s>
<s>
On	O
the	O
back	O
of	O
the	O
computer	B-General_Concept
case	I-General_Concept
,	O
some	O
major	O
changes	O
were	O
made	O
to	O
the	O
AT	O
standard	O
.	O
</s>
<s>
Originally	O
AT	O
style	O
cases	O
had	O
only	O
a	O
keyboard	B-Device
connector	O
and	O
expansion	O
slots	O
for	O
add-on	O
card	O
backplates	O
.	O
</s>
<s>
Any	O
other	O
onboard	O
interfaces	O
(	O
such	O
as	O
serial	B-Protocol
and	O
parallel	B-Device
ports	I-Device
)	O
had	O
to	O
be	O
connected	O
via	O
flying	O
leads	O
to	O
connectors	O
which	O
were	O
mounted	O
either	O
on	O
spaces	O
provided	O
by	O
the	O
case	O
or	O
brackets	O
placed	O
in	O
unused	O
expansion	O
slot	O
positions	O
.	O
</s>
<s>
ATX	B-Architecture
allowed	O
each	O
motherboard	B-Device
manufacturer	O
to	O
put	O
these	O
ports	O
in	O
a	O
rectangular	O
area	O
on	O
the	O
back	O
of	O
the	O
system	O
with	O
an	O
arrangement	O
they	O
could	O
define	O
themselves	O
,	O
though	O
a	O
number	O
of	O
general	O
patterns	O
depending	O
on	O
what	O
ports	O
the	O
motherboard	B-Device
offers	O
have	O
been	O
followed	O
by	O
most	O
manufacturers	O
.	O
</s>
<s>
If	O
necessary	O
,	O
I/O	O
plates	O
can	O
be	O
replaced	O
to	O
suit	O
a	O
motherboard	B-Device
that	O
is	O
being	O
fitted	O
;	O
the	O
I/O	O
plates	O
are	O
usually	O
included	O
with	O
motherboards	B-Device
not	O
designed	O
for	O
a	O
particular	O
computer	O
.	O
</s>
<s>
Panels	O
were	O
made	O
that	O
allowed	O
fitting	O
an	O
AT	O
motherboard	B-Device
in	O
an	O
ATX	B-Architecture
case	O
.	O
</s>
<s>
Some	O
ATX	B-Architecture
motherboards	I-Architecture
come	O
with	O
an	O
integrated	O
I/O	O
plate	O
.	O
</s>
<s>
ATX	B-Architecture
also	O
made	O
the	O
PS/2	B-Protocol
-style	I-Protocol
mini-DIN	B-Protocol
keyboard	B-Protocol
and	I-Protocol
mouse	I-Protocol
connectors	I-Protocol
ubiquitous	O
.	O
</s>
<s>
AT	O
systems	O
used	O
a	O
5-pin	O
DIN	B-Architecture
connector	I-Architecture
for	O
the	O
keyboard	B-Device
and	O
were	O
generally	O
used	O
with	O
serial	B-Protocol
port	I-Protocol
mice	O
(	O
although	O
PS/2	B-Protocol
mouse	I-Protocol
ports	O
were	O
also	O
found	O
on	O
some	O
systems	O
)	O
.	O
</s>
<s>
Many	O
modern	O
motherboards	B-Device
are	O
phasing	O
out	O
the	O
PS/2	B-Protocol
-style	I-Protocol
keyboard	B-Protocol
and	I-Protocol
mouse	I-Protocol
connectors	I-Protocol
in	O
favor	O
of	O
the	O
more	O
modern	O
Universal	B-Protocol
Serial	I-Protocol
Bus	I-Protocol
.	O
</s>
<s>
Other	O
legacy	O
connectors	O
that	O
are	O
slowly	O
being	O
phased	O
out	O
of	O
modern	O
ATX	B-Architecture
motherboards	I-Architecture
include	O
25-pin	O
parallel	B-Device
ports	I-Device
and	O
9-pin	O
RS-232	O
serial	B-Protocol
ports	I-Protocol
.	O
</s>
<s>
In	O
their	O
place	O
are	O
onboard	O
peripheral	O
ports	O
such	O
as	O
Ethernet	O
,	O
FireWire	B-Protocol
,	O
eSATA	O
,	O
audio	B-Device
ports	I-Device
(	O
both	O
analog	O
and	O
S/PDIF	O
)	O
,	O
video	O
(	O
analog	O
D-sub	B-Protocol
,	O
DVI	B-Protocol
,	O
HDMI	B-Protocol
,	O
or	O
DisplayPort	B-Protocol
)	O
,	O
extra	O
USB	B-Protocol
ports	O
,	O
and	O
Wi-Fi	O
.	O
</s>
<s>
A	O
notable	O
issue	O
with	O
the	O
ATX	B-Architecture
specification	O
was	O
that	O
it	O
was	O
last	O
revised	O
when	O
power	O
supplies	O
were	O
normally	O
placed	O
at	O
the	O
top	O
,	O
rather	O
than	O
the	O
bottom	O
,	O
of	O
computer	B-General_Concept
cases	I-General_Concept
.	O
</s>
<s>
Several	O
ATX-derived	O
designs	O
have	O
been	O
specified	O
that	O
use	O
the	O
same	O
power	O
supply	O
,	O
mountings	O
and	O
basic	O
back	O
panel	O
arrangement	O
,	O
but	O
set	O
different	O
standards	O
for	O
the	O
size	O
of	O
the	O
board	O
and	O
number	O
of	O
expansion	O
slots	O
.	O
</s>
<s>
Standard	O
ATX	B-Architecture
provides	O
seven	O
slots	O
at	O
spacing	O
;	O
the	O
popular	O
microATX	B-Device
size	O
removes	O
and	O
three	O
slots	O
,	O
leaving	O
four	O
.	O
</s>
<s>
AOpen	O
has	O
conflated	O
the	O
term	O
Mini	B-Device
ATX	I-Device
with	O
a	O
more	O
recent	O
design	O
.	O
</s>
<s>
Since	O
references	O
to	O
Mini	B-Device
ATX	I-Device
have	O
been	O
removed	O
from	O
ATX	B-Architecture
specifications	O
since	O
the	O
adoption	O
of	O
microATX	B-Device
,	O
the	O
AOpen	O
definition	O
is	O
the	O
more	O
contemporary	O
term	O
and	O
the	O
one	O
listed	O
above	O
is	O
apparently	O
only	O
of	O
historical	O
significance	O
.	O
</s>
<s>
This	O
sounds	O
contradictory	O
to	O
the	O
now	O
common	O
Mini-ITX	B-Architecture
standard	O
(	O
)	O
,	O
which	O
is	O
a	O
potential	O
source	O
of	O
confusion	O
.	O
</s>
<s>
A	O
number	O
of	O
manufacturers	O
have	O
added	O
one	O
to	O
three	O
additional	O
expansion	O
slots	O
(	O
at	O
the	O
standard	O
0.8	O
inch	O
spacing	O
)	O
to	O
the	O
standard	O
12-inch	O
ATX	B-Architecture
motherboard	I-Architecture
width	O
.	O
</s>
<s>
Form	O
factors	O
considered	O
obsolete	O
in	O
1999	O
included	O
Baby-AT	B-Device
,	O
full	O
size	O
AT	O
,	O
and	O
the	O
semi-proprietary	O
LPX	B-Device
for	O
low-profile	O
cases	O
.	O
</s>
<s>
Proprietary	O
motherboard	B-Device
designs	O
such	O
as	O
those	O
by	O
Compaq	O
,	O
Packard-Bell	O
,	O
Hewlett	O
Packard	O
and	O
others	O
existed	O
,	O
and	O
were	O
not	O
interchangeable	O
with	O
multi-manufacturer	O
boards	O
and	O
cases	O
.	O
</s>
<s>
Portable	O
and	O
notebook	O
computers	O
and	O
some	O
19-inch	O
rackmount	O
servers	O
have	O
custom	O
motherboards	B-Device
unique	O
to	O
their	O
particular	O
products	O
.	O
</s>
<s>
ATX	B-Architecture
Intel	O
1995	O
12	O
×	O
9.6	O
in	O
(	O
305	O
×	O
244	O
mm	O
)	O
7	O
Original	O
,	O
successor	O
to	O
AT	O
motherboard	B-Device
Proprietary	O
,	O
specific	O
to	O
crypto-mining	O
specific	O
motherboards	B-Device
2011	O
12	O
×	O
8	O
in	O
(	O
305	O
×	O
203	O
mm	O
)	O
3	O
3	O
double-slot	O
add-in	O
cards	O
with	O
1	O
slots	O
of	O
free	O
space	O
in	O
between	O
SSI	B-Device
CEB	I-Device
SSI	B-Device
12	O
×	O
10.5	O
in	O
(	O
305	O
×	O
267	O
mm	O
)	O
7	O
Compact	B-Device
Electronics	I-Device
Bay	I-Device
SSI	B-Device
MEB	I-Device
SSI	B-Device
2011	O
16.2	O
×	O
13	O
in	O
(	O
411	O
×	O
330	O
mm	O
)	O
12	O
Midrange	O
Electronics	O
Bay	O
SSI	B-Device
EEB	I-Device
SSI	B-Device
12	O
×	O
13	O
in	O
(	O
305	O
×	O
330	O
mm	O
)	O
7	O
Enterprise	B-Device
Electronics	I-Device
Bay	I-Device
SSI	B-Device
TEB	I-Device
SSI	B-Device
12	O
×	O
10.5	O
in	O
(	O
305	O
×	O
267	O
mm	O
)	O
7	O
Thin	O
Electronics	O
Bay	O
,	O
for	O
rack-mount	O
,	O
has	O
board	O
component	O
height	O
specification	O
microATX	B-Device
Intel	O
1997	O
9.6	O
×	O
9.6	O
in	O
(	O
244	O
×	O
244	O
mm	O
)	O
4	O
Fits	O
in	O
ATX	B-Architecture
,	O
and	O
EATX	O
cases	O
.	O
</s>
<s>
FlexATX	B-Device
Intel	O
1997	O
9	O
×	O
7.5	O
in	O
(	O
229	O
×	O
191	O
mm	O
)	O
3	O
Extended	B-Architecture
ATX	I-Architecture
(	O
standard	O
)	O
Supermicro	O
/	O
Asus	O
12	O
×	O
13	O
in	O
(	O
305	O
×	O
330	O
mm	O
)	O
7	O
Screw	O
holes	O
not	O
completely	O
compatible	O
with	O
some	O
ATX	B-Architecture
cases	O
.	O
</s>
<s>
Extended	B-Architecture
ATX	I-Architecture
(	O
commonly	O
)	O
12	O
×	O
10.1	O
in	O
(	O
305	O
×	O
257	O
mm	O
)	O
12	O
×	O
10.4	O
in	O
(	O
305	O
×	O
264	O
mm	O
)	O
12	O
×	O
10.5	O
in	O
(	O
305	O
×	O
267	O
mm	O
)	O
12	O
×	O
10.7	O
in	O
(	O
305	O
×	O
272	O
mm	O
)	O
7	O
ATX	B-Architecture
pattern	O
screw	O
holes	O
EE-ATXSupermicro	O
13.68	O
×	O
13	O
in	O
(	O
347	O
×	O
330	O
mm	O
)	O
7	O
Enhanced	O
Extended	B-Architecture
ATX	I-Architecture
Ultra	B-Device
ATX	I-Device
Foxconn	O
2008	O
14.4	O
×	O
9.6	O
in	O
(	O
366	O
×	O
244	O
mm	O
)	O
10	O
Intended	O
for	O
multiple	O
double-slot	O
video	O
cards	O
,	O
and	O
dual	O
CPUs	O
.	O
</s>
<s>
XL-ATX	O
EVGA	O
2009	O
13.5	O
×	O
10.3	O
in	O
(	O
343	O
×	O
262	O
mm	O
)	O
9	O
XL-ATX	O
Gigabyte	O
2010	O
13.58	O
x	O
10.31	O
in	O
(	O
345	O
x	O
262	O
mm	O
)	O
7	O
XL-ATX	O
MSI	O
2010	O
13.6	O
×	O
10.4	O
in	O
(	O
345	O
×	O
264	O
mm	O
)	O
7	O
WTX	B-Device
Intel	O
1998	O
14	O
×	O
16.75	O
in	O
(	O
356	O
×	O
425	O
mm	O
)	O
.	O
</s>
<s>
9	O
Discontinued	O
2008	O
Mini-ITX	B-Architecture
VIA	O
2001	O
6.7	O
x	O
6.7in	O
(	O
170	O
×	O
170	O
mm	O
)	O
.	O
</s>
<s>
1	O
Originally	O
designed	O
for	O
home	O
theatre	O
or	O
other	O
fanless	O
applications	O
Mini-DTX	B-Device
AMD	O
2007	O
8	O
×	O
6.7	O
in	O
(	O
203	O
×	O
170	O
mm	O
)	O
2	O
Derived	O
from	O
Mini-ITX	B-Architecture
and	O
DTX	B-Device
BTX	B-Device
Intel	O
2004	O
12.8	O
×	O
10.5	O
in	O
(	O
325	O
×	O
267	O
mm	O
)	O
7	O
Canceled	O
2006	O
.	O
</s>
<s>
Not	O
generally	O
compatible	O
with	O
ATX	B-Architecture
mounting	O
.	O
</s>
<s>
Although	O
true	O
E-ATX	O
is	O
most	O
motherboard	B-Device
manufacturers	O
also	O
refer	O
to	O
motherboards	B-Device
with	O
measurements	O
,	O
,	O
and	O
as	O
E-ATX	O
.	O
</s>
<s>
While	O
E-ATX	O
and	O
SSI	B-Device
EEB	I-Device
(	O
Server	O
System	O
Infrastructure	O
(	O
SSI	B-Device
)	O
Forum	O
's	O
Enterprise	B-Device
Electronics	I-Device
Bay	I-Device
(	O
EEB	O
)	O
)	O
share	O
the	O
same	O
dimensions	O
,	O
the	O
screw	O
holes	O
of	O
the	O
two	O
standards	O
do	O
not	O
all	O
align	O
;	O
rendering	O
them	O
incompatible	O
.	O
</s>
<s>
In	O
2008	O
,	O
Foxconn	O
unveiled	O
a	O
Foxconn	O
F1	O
motherboard	B-Device
prototype	O
,	O
which	O
has	O
the	O
same	O
width	O
as	O
a	O
standard	O
ATX	B-Architecture
motherboard	I-Architecture
,	O
but	O
an	O
extended	O
14.4	O
"	O
length	O
to	O
accommodate	O
10	O
slots	O
.	O
</s>
<s>
The	O
firm	O
called	O
the	O
new	O
design	O
of	O
this	O
motherboard	B-Device
"	O
Ultra	B-Device
ATX	I-Device
"	O
in	O
its	O
CES	O
2008	O
showing	O
.	O
</s>
<s>
Also	O
unveiled	O
during	O
the	O
January	O
2008	O
CES	O
was	O
the	O
Lian	O
Li	O
Armorsuit	O
PC-P80	O
case	O
with	O
10	O
slots	O
designed	O
for	O
the	O
motherboard	B-Device
.	O
</s>
<s>
The	O
name	O
"	O
XL-ATX	O
"	O
has	O
been	O
used	O
by	O
at	O
least	O
three	O
companies	O
in	O
different	O
ways	O
:	O
</s>
<s>
In	O
September	O
2009	O
,	O
EVGA	O
Corporation	O
had	O
already	O
released	O
a	O
"	O
XL-ATX	O
"	O
motherboard	B-Device
as	O
its	O
EVGA	O
X58	O
Classified	O
4-Way	O
SLI	O
.	O
</s>
<s>
In	O
April	O
2010	O
,	O
Gigabyte	O
announced	O
its	O
GA-890FXA-UD7	O
motherboard	B-Device
that	O
allowed	O
all	O
seven	O
slots	O
to	O
be	O
moved	O
downward	O
by	O
one	O
slot	O
position	O
.	O
</s>
<s>
In	O
2010	O
,	O
EVGA	O
Corporation	O
released	O
a	O
new	O
motherboard	B-Device
,	O
the	O
"	O
Super	O
Record	O
2	O
"	O
,	O
or	O
SR-2	O
,	O
whose	O
size	O
surpasses	O
that	O
of	O
the	O
"	O
EVGA	O
X58	O
Classified	O
4-Way	O
SLI	O
"	O
.	O
</s>
<s>
Intel	B-Device
Xeon	I-Device
)	O
,	O
similar	O
to	O
that	O
of	O
the	O
Intel	B-Device
Skulltrail	I-Device
motherboard	B-Device
that	O
could	O
accommodate	O
two	O
Intel	B-Device
Core2	I-Device
Quad	O
processors	O
and	O
has	O
a	O
total	O
of	O
seven	O
PCI-E	O
slots	O
and	O
12	O
DDR3	O
RAM	O
slots	O
.	O
</s>
<s>
The	O
ATX	B-Architecture
specification	O
requires	O
the	O
power	O
supply	O
to	O
produce	O
three	O
main	O
outputs	O
,	O
+	O
3.3V	O
,	O
+5V	O
and	O
+12V	O
.	O
</s>
<s>
The	O
−12V	O
supply	O
is	O
primarily	O
used	O
to	O
provide	O
the	O
negative	O
supply	O
voltage	O
for	O
RS-232	O
ports	O
and	O
is	O
also	O
used	O
by	O
one	O
pin	O
on	O
conventional	B-Protocol
PCI	I-Protocol
slots	O
primarily	O
to	O
provide	O
a	O
reference	O
voltage	O
for	O
some	O
models	O
of	O
sound	B-Device
cards	I-Device
.	O
</s>
<s>
The	O
5VSB	O
supply	O
is	O
used	O
to	O
produce	O
trickle	O
power	O
to	O
provide	O
the	O
soft-power	O
feature	O
of	O
ATX	B-Architecture
when	O
a	O
PC	O
is	O
turned	O
off	O
,	O
as	O
well	O
as	O
powering	O
the	O
real-time	O
clock	O
to	O
conserve	O
the	O
charge	O
of	O
the	O
CMOS	O
battery	O
.	O
</s>
<s>
A	O
−5V	O
output	O
was	O
originally	O
required	O
because	O
it	O
was	O
supplied	O
on	O
the	O
ISA	B-Architecture
bus	I-Architecture
;	O
it	O
was	O
removed	O
in	O
later	O
versions	O
of	O
the	O
ATX	B-Architecture
standard	O
,	O
as	O
it	O
became	O
obsolete	O
with	O
the	O
removal	O
of	O
the	O
ISA	B-Architecture
bus	I-Architecture
expansion	O
slots	O
(	O
the	O
ISA	B-Architecture
bus	I-Architecture
itself	O
is	O
still	O
found	O
in	O
any	O
computer	O
which	O
is	O
compatible	O
with	O
the	O
old	O
IBM	O
PC	O
specification	O
;	O
e.g.	O
,	O
not	O
found	O
in	O
the	O
PlayStation	B-Architecture
4	I-Architecture
)	O
.	O
</s>
<s>
Originally	O
,	O
the	O
motherboard	B-Device
was	O
powered	O
by	O
one	O
20-pin	O
connector	O
.	O
</s>
<s>
An	O
ATX	B-Architecture
power	O
supply	O
provides	O
a	O
number	O
of	O
peripheral	O
power	O
connectors	O
and	O
(	O
in	O
modern	O
systems	O
)	O
two	O
connectors	O
for	O
the	O
motherboard	B-Device
:	O
an	O
8-pin	O
(	O
or	O
4+	O
4-pin	O
)	O
auxiliary	O
connector	O
providing	O
additional	O
power	O
to	O
the	O
CPU	O
and	O
a	O
main	O
24-pin	O
power	O
supply	O
connector	O
,	O
an	O
extension	O
of	O
the	O
original	O
20-pin	O
version	O
.	O
</s>
<s>
20-pin	O
MOLEX	O
39-29-9202	O
at	O
the	O
motherboard	B-Device
.	O
</s>
<s>
PS_ON#	O
(	O
power	O
on	O
)	O
is	O
a	O
signal	O
from	O
the	O
motherboard	B-Device
to	O
the	O
power	O
supply	O
.	O
</s>
<s>
When	O
the	O
line	O
is	O
connected	O
to	O
ground	O
(	O
by	O
the	O
motherboard	B-Device
)	O
,	O
the	O
power	O
supply	O
turns	O
on	O
.	O
</s>
<s>
+	O
3.3	O
V	O
sense	O
should	O
be	O
connected	O
to	O
the	O
+	O
3.3V	O
on	O
the	O
motherboard	B-Device
or	O
its	O
power	O
connector	O
.	O
</s>
<s>
Some	O
manufacturers	O
also	O
provided	O
a	O
+5	O
V	O
sense	O
wire	O
(	O
typically	O
colored	O
pink	O
)	O
connected	O
to	O
one	O
of	O
the	O
red	O
+5V	O
wires	O
on	O
some	O
models	O
of	O
power	O
supply	O
;	O
however	O
,	O
the	O
inclusion	O
of	O
such	O
wire	O
was	O
a	O
non-standard	O
practice	O
and	O
was	O
never	O
part	O
of	O
any	O
official	O
ATX	B-Architecture
standard	O
.	O
</s>
<s>
As	O
large	O
server	O
motherboards	B-Device
and	O
3D	O
graphics	O
cards	O
have	O
required	O
progressively	O
more	O
and	O
more	O
power	O
to	O
operate	O
,	O
it	O
has	O
been	O
necessary	O
to	O
revise	O
and	O
extend	O
the	O
standard	O
beyond	O
the	O
original	O
20-pin	O
connector	O
,	O
to	O
allow	O
more	O
current	O
using	O
multiple	O
additional	O
pins	O
in	O
parallel	O
.	O
</s>
<s>
ATX	B-Architecture
power	O
supplies	O
generally	O
have	O
the	O
dimensions	O
of	O
,	O
with	O
the	O
width	O
and	O
height	O
being	O
the	O
same	O
as	O
the	O
preceding	O
LPX	B-Device
(	O
Low	O
Profile	O
eXtension	O
)	O
form	O
factor	O
(	O
which	O
are	O
often	O
incorrectly	O
referred	O
to	O
as	O
"	O
AT	O
"	O
power	O
supplies	O
due	O
to	O
their	O
ubiquitous	O
use	O
in	O
later	O
AT	O
and	O
Baby	O
AT	O
systems	O
,	O
even	O
though	O
the	O
actual	O
AT	O
and	O
Baby	O
AT	O
power	O
supply	O
form	O
factors	O
were	O
physically	O
larger	O
)	O
and	O
share	O
a	O
common	O
mounting	O
layout	O
of	O
four	O
screws	O
arranged	O
on	O
the	O
back	O
side	O
of	O
the	O
unit	O
.	O
</s>
<s>
Later	O
AT	O
(	O
so-called	O
"	O
Baby	O
AT	O
"	O
)	O
and	O
LPX	B-Device
style	O
computer	B-General_Concept
cases	I-General_Concept
have	O
a	O
power	O
button	O
that	O
is	O
directly	O
connected	O
to	O
the	O
system	O
computer	O
power	O
supply	O
(	O
PSU	O
)	O
.	O
</s>
<s>
An	O
ATX	B-Architecture
power	O
supply	O
is	O
typically	O
controlled	O
by	O
an	O
electronic	O
switch	O
connected	O
to	O
the	O
power	O
button	O
on	O
the	O
computer	B-General_Concept
case	I-General_Concept
and	O
allows	O
the	O
computer	O
to	O
be	O
turned	O
off	O
by	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
In	O
addition	O
,	O
many	O
ATX	B-Architecture
power	O
supplies	O
have	O
a	O
manual	O
switch	O
on	O
the	O
back	O
that	O
also	O
ensures	O
no	O
power	O
is	O
being	O
sent	O
to	O
the	O
components	O
.	O
</s>
<s>
The	O
power	O
supply	O
's	O
connection	O
to	O
the	O
motherboard	B-Device
was	O
changed	O
from	O
the	O
older	O
AT	O
and	O
LPX	B-Device
standards	O
;	O
AT	O
and	O
LPX	B-Device
had	O
two	O
similar	O
connectors	O
that	O
could	O
be	O
accidentally	O
interchanged	O
by	O
forcing	O
the	O
different	O
keyed	O
connectors	O
into	O
place	O
,	O
usually	O
causing	O
short-circuits	O
and	O
irreversible	O
damage	O
to	O
the	O
motherboard	B-Device
(	O
the	O
rule	O
of	O
thumb	O
for	O
safe	O
operation	O
was	O
to	O
connect	O
the	O
side-by-side	O
connectors	O
with	O
the	O
black	O
wires	O
together	O
)	O
.	O
</s>
<s>
ATX	B-Architecture
uses	O
one	O
large	O
,	O
keyed	O
connector	O
which	O
can	O
not	O
be	O
connected	O
incorrectly	O
.	O
</s>
<s>
The	O
new	O
connector	O
also	O
provides	O
a	O
3.3volt	O
source	O
,	O
removing	O
the	O
need	O
for	O
motherboards	B-Device
to	O
derive	O
this	O
voltage	O
from	O
the	O
5V	O
rail	O
.	O
</s>
<s>
Some	O
motherboards	B-Device
,	O
particularly	O
those	O
manufactured	O
after	O
the	O
introduction	O
of	O
ATX	B-Architecture
but	O
while	O
LPX	B-Device
equipment	O
was	O
still	O
in	O
use	O
,	O
support	O
both	O
LPX	B-Device
and	O
ATX	B-Architecture
PSUs	O
.	O
</s>
<s>
If	O
using	O
an	O
ATX	B-Architecture
PSU	O
for	O
purposes	O
other	O
than	O
powering	O
an	O
ATX	B-Architecture
motherboard	I-Architecture
,	O
power	O
can	O
be	O
fully	O
turned	O
on	O
(	O
it	O
is	O
always	O
partly	O
on	O
to	O
operate	O
"	O
wake-up	O
"	O
devices	O
)	O
by	O
shorting	O
the	O
"	O
power-on	O
"	O
pin	O
on	O
the	O
ATX	B-Architecture
connector	O
(	O
pin	O
16	O
,	O
green	O
wire	O
)	O
to	O
a	O
black	O
wire	O
(	O
ground	O
)	O
,	O
which	O
is	O
what	O
the	O
power	O
button	O
on	O
an	O
ATX	B-Architecture
system	O
does	O
.	O
</s>
<s>
An	O
ATX	B-Architecture
power	O
supply	O
is	O
not	O
a	O
replacement	O
for	O
a	O
current-limited	O
bench	O
laboratory	O
DC	O
power	O
supply	O
;	O
instead	O
it	O
is	O
better	O
described	O
as	O
a	O
bulk	O
DC	O
power	O
supply	O
.	O
</s>
<s>
The	O
original	O
ATX	B-Architecture
specification	O
called	O
for	O
a	O
power	O
supply	O
to	O
be	O
located	O
near	O
to	O
the	O
CPU	O
with	O
the	O
power	O
supply	O
fan	O
drawing	O
in	O
cooling	O
air	O
from	O
outside	O
the	O
chassis	O
and	O
directing	O
it	O
onto	O
the	O
processor	O
.	O
</s>
<s>
This	O
recommendation	O
was	O
removed	O
from	O
later	O
specifications	O
;	O
modern	O
ATX	B-Architecture
power	O
supplies	O
usually	O
exhaust	O
air	O
from	O
the	O
case	O
.	O
</s>
<s>
ATX	B-Architecture
,	O
introduced	O
in	O
late	O
1995	O
,	O
defined	O
three	O
types	O
of	O
power	O
connectors	O
:	O
</s>
<s>
4-pin	O
"	O
Molex	O
connector	O
"	O
–	O
transferred	O
directly	O
from	O
AT	O
standard	O
:	O
+5V	O
and	O
+12V	O
for	O
P-ATA	B-Protocol
hard	O
disks	O
,	O
CD-ROMs	O
,	O
5.25inch	O
floppy	O
drives	O
and	O
other	O
peripherals	O
.	O
</s>
<s>
4-pin	O
Berg	B-Device
floppy	I-Device
connector	I-Device
–	O
transferred	O
directly	O
from	O
AT	O
standard	O
:	O
+5V	O
and	O
+12V	O
for	O
3.5inch	O
floppy	O
drives	O
and	O
other	O
peripherals	O
.	O
</s>
<s>
20-pin	O
Molex	O
Mini-fit	O
Jr.	O
ATX	B-Architecture
motherboard	I-Architecture
connector	O
–	O
new	O
to	O
the	O
ATX	B-Architecture
standard	O
.	O
</s>
<s>
A	O
supplemental	O
6-pin	O
AUX	O
connector	O
providing	O
additional	O
3.3V	O
and	O
5V	O
supplies	O
to	O
the	O
motherboard	B-Device
,	O
if	O
needed	O
.	O
</s>
<s>
This	O
was	O
used	O
to	O
power	O
the	O
CPU	O
in	O
motherboards	B-Device
with	O
CPU	O
voltage	O
regulator	O
modules	O
which	O
required	O
3.3volt	O
and/or	O
5volt	O
rails	O
and	O
could	O
not	O
get	O
enough	O
power	O
through	O
the	O
regular	O
20-pin	O
header	O
.	O
</s>
<s>
The	O
power	O
distribution	O
specification	O
defined	O
that	O
most	O
of	O
the	O
PSU	O
's	O
power	O
should	O
be	O
provided	O
on	O
5V	O
and	O
3.3V	O
rails	O
,	O
because	O
most	O
of	O
the	O
electronic	O
components	O
(	O
CPU	O
,	O
RAM	O
,	O
chipset	O
,	O
PCI	B-Protocol
,	O
AGP	B-Architecture
and	O
ISA	B-Architecture
cards	I-Architecture
)	O
used	O
5V	O
or	O
3.3V	O
for	O
power	O
supply	O
.	O
</s>
<s>
The	O
12V	O
rail	O
was	O
only	O
used	O
by	O
computer	B-Application
fans	I-Application
and	O
motors	O
of	O
peripheral	O
devices	O
(	O
HDD	O
,	O
FDD	O
,	O
CD-ROM	O
,	O
etc	O
.	O
)	O
</s>
<s>
While	O
designing	O
the	O
Pentium4	B-General_Concept
platform	O
in	O
1999/2000	O
,	O
the	O
standard	O
20-pin	O
ATX	B-Architecture
power	I-Architecture
connector	I-Architecture
was	O
found	O
insufficient	O
to	O
meet	O
increasing	O
power-line	O
requirements	O
;	O
the	O
standard	O
was	O
significantly	O
revised	O
into	O
ATX12V	O
1.0	O
(	O
ATX12V	O
1.x	O
is	O
sometimes	O
inaccurately	O
called	O
ATX-P4	O
)	O
.	O
</s>
<s>
However	O
,	O
some	O
early	O
model	O
Athlon	O
XP	O
and	O
MP	O
boards	O
(	O
including	O
some	O
server	O
boards	O
)	O
and	O
later	O
model	O
lower-end	O
motherboards	B-Device
do	O
not	O
have	O
the	O
4-pin	O
connector	O
as	O
described	O
below	O
.	O
</s>
<s>
Numbering	O
of	O
the	O
ATX	B-Architecture
revisions	O
may	O
be	O
a	O
little	O
confusing	O
:	O
ATX	B-Architecture
refers	O
to	O
the	O
design	O
,	O
and	O
goes	O
up	O
to	O
version	O
2.2	O
in	O
2004	O
(	O
with	O
the	O
24	O
pins	O
of	O
ATX12V	O
2.0	O
)	O
,	O
while	O
ATX12V	O
describes	O
only	O
the	O
PSU	O
.	O
</s>
<s>
For	O
instance	O
,	O
ATX	B-Architecture
2.03	O
is	O
quite	O
commonly	O
seen	O
on	O
PSUs	O
from	O
2000	O
and	O
2001	O
and	O
often	O
includes	O
the	O
P4	O
12V	O
connector	O
,	O
even	O
if	O
the	O
norm	O
itself	O
did	O
not	O
define	O
it	O
yet	O
.	O
</s>
<s>
Formally	O
called	O
the	O
+12	O
V	O
Power	O
Connector	O
,	O
this	O
is	O
commonly	O
referred	O
to	O
as	O
the	O
P4	O
connector	O
because	O
this	O
was	O
first	O
needed	O
to	O
support	O
the	O
Pentium	B-General_Concept
4	I-General_Concept
processor	O
.	O
</s>
<s>
Before	O
the	O
Pentium4	B-General_Concept
,	O
processors	O
were	O
generally	O
powered	O
from	O
the	O
5V	O
rail	O
.	O
</s>
<s>
It	O
is	O
infeasible	O
to	O
provide	O
power	O
at	O
such	O
low	O
voltages	O
and	O
high	O
currents	O
from	O
a	O
standard	O
system	O
power	O
supply	O
,	O
so	O
the	O
Pentium4	B-General_Concept
established	O
the	O
practice	O
of	O
generating	O
it	O
with	O
a	O
DC-to-DC	O
converter	O
on	O
the	O
motherboard	B-Device
next	O
to	O
the	O
processor	O
,	O
powered	O
by	O
the	O
4-pin	O
12V	O
connector	O
.	O
</s>
<s>
This	O
voltage	O
was	O
required	O
by	O
the	O
ISA	B-Architecture
bus	I-Architecture
,	O
which	O
is	O
no	O
longer	O
present	O
on	O
almost	O
all	O
modern	O
computers	O
.	O
</s>
<s>
Introduction	O
of	O
Serial	B-Protocol
ATA	O
power	O
connector	O
(	O
but	O
defined	O
as	O
optional	O
)	O
.	O
</s>
<s>
In	O
particular	O
,	O
PCI	B-Protocol
Express	O
expansion	O
cards	O
take	O
much	O
of	O
their	O
power	O
from	O
the	O
12V	O
rail	O
(	O
up	O
to	O
5.5A	O
)	O
,	O
while	O
the	O
older	O
AGP	B-Architecture
graphics	O
cards	O
took	O
only	O
up	O
to	O
1A	O
on	O
12V	O
and	O
up	O
to	O
6A	O
on	O
3.3V	O
.	O
</s>
<s>
The	O
CPU	O
is	O
also	O
driven	O
by	O
a	O
12V	O
rail	O
,	O
while	O
it	O
was	O
done	O
by	O
a	O
5V	O
rail	O
on	O
older	O
PCs	O
(	O
before	O
the	O
Pentium4	B-General_Concept
)	O
.	O
</s>
<s>
The	O
power	O
demands	O
of	O
PCI	B-Protocol
Express	O
were	O
incorporated	O
in	O
ATX12V	O
2.0	O
(	O
introduced	O
in	O
February	O
2003	O
)	O
,	O
which	O
defined	O
quite	O
different	O
power	O
distribution	O
from	O
ATX12V	O
1.x	O
:	O
</s>
<s>
The	O
ATX	B-Architecture
motherboard	I-Architecture
connector	O
was	O
extended	O
to	O
24	O
pins	O
.	O
</s>
<s>
The	O
six-pin	O
AUX	O
connector	O
from	O
ATX12V	O
1.x	O
was	O
removed	O
because	O
the	O
extra	O
3.3V	O
and	O
5V	O
circuits	O
which	O
it	O
provided	O
are	O
now	O
incorporated	O
in	O
the	O
24-pin	O
ATX	B-Architecture
motherboard	I-Architecture
connector	O
.	O
</s>
<s>
The	O
power	O
supply	O
is	O
required	O
to	O
include	O
a	O
Serial	B-Protocol
ATA	O
power	O
cable	O
.	O
</s>
<s>
Also	O
released	O
in	O
March	O
2005	O
it	O
includes	O
corrections	O
and	O
specifies	O
High	O
Current	O
Series	O
wire	O
terminals	O
for	O
24-pin	O
ATX	B-Architecture
motherboard	I-Architecture
and	O
4-pin	O
+12V	O
power	O
connectors	O
.	O
</s>
<s>
The	O
specifications	O
for	O
ATXV12	O
2.53	O
were	O
released	O
in	O
May	O
2020	O
and	O
constitute	O
another	O
minor	O
update	O
to	O
the	O
ATX	B-Architecture
standard	O
.	O
</s>
<s>
The	O
specifications	O
for	O
ATX	B-Architecture
3.0	O
were	O
released	O
in	O
February	O
2022	O
.	O
</s>
<s>
Standing	O
for	O
ATX	B-Architecture
12-volt-only	O
,	O
this	O
is	O
a	O
new	O
specification	O
published	O
by	O
Intel	O
in	O
2019	O
,	O
aimed	O
at	O
pre-built	O
systems	O
in	O
the	O
first	O
run	O
,	O
and	O
stricter	O
power	O
efficiency	O
requirements	O
by	O
the	O
California	O
Energy	O
Commission	O
going	O
into	O
effect	O
in	O
2021	O
.	O
</s>
<s>
ATX12VO	O
introduces	O
a	O
new	O
10-pin	O
connector	O
to	O
supply	O
the	O
motherboard	B-Device
,	O
replacing	O
the	O
24-pin	O
ATX12V	O
connector	O
.	O
</s>
<s>
This	O
greatly	O
simplifies	O
power	O
supplies	O
,	O
but	O
moves	O
DC-to-DC	O
conversion	O
and	O
some	O
connectors	O
to	O
the	O
motherboard	B-Device
instead	O
.	O
</s>
<s>
Notably	O
,	O
SATA	O
power	O
connectors	O
,	O
which	O
include	O
3.3V	O
and	O
5V	O
pins	O
,	O
need	O
to	O
move	O
to	O
the	O
motherboard	B-Device
instead	O
of	O
being	O
connected	O
directly	O
to	O
the	O
power	O
supply	O
.	O
</s>
<s>
SFX	O
is	O
merely	O
a	O
design	O
for	O
a	O
small	B-Device
form	I-Device
factor	I-Device
(	O
SFF	O
)	O
power	O
supply	O
casing	O
(	O
such	O
as	O
those	O
using	O
microATX	B-Device
,	O
FlexATX	B-Device
,	O
nano-ITX	B-Device
,	O
mini-ITX	B-Architecture
,	O
and	O
NLX	B-Device
)	O
,	O
with	O
the	O
power	O
specifications	O
almost	O
identical	O
to	O
ATX	B-Architecture
.	O
</s>
<s>
Thus	O
,	O
an	O
SFX	O
power	O
supply	O
is	O
mostly	O
pin-compatible	O
with	O
the	O
ATX	B-Architecture
power	O
supply	O
as	O
the	O
main	O
difference	O
is	O
its	O
reduced	O
dimensions	O
;	O
the	O
only	O
electrical	O
difference	O
is	O
that	O
the	O
SFX	O
specifications	O
do	O
not	O
require	O
the	O
−5V	O
rail	O
.	O
</s>
<s>
Since	O
−5V	O
is	O
required	O
only	O
by	O
some	O
ISA-bus	O
expansion	O
cards	O
,	O
this	O
is	O
not	O
an	O
issue	O
with	O
modern	O
hardware	O
and	O
decreases	O
productions	O
costs	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
ATX	B-Architecture
pin	O
20	O
,	O
which	O
carried	O
−5V	O
,	O
is	O
absent	O
in	O
current	O
power	O
supplies	O
;	O
it	O
was	O
optional	O
in	O
ATX	B-Architecture
and	O
ATX12V	O
version	O
1.2	O
and	O
deleted	O
as	O
of	O
ATX	B-Architecture
version	O
1.3	O
.	O
</s>
<s>
SFX	O
has	O
dimensions	O
of	O
125×	O
63.5	O
×	O
100mm	O
(	O
width×	O
height×	O
depth	O
)	O
,	O
with	O
a	O
60mm	O
fan	O
,	O
compared	O
with	O
the	O
standard	O
ATX	B-Architecture
dimensions	O
of	O
150×	O
86×	O
140mm	O
.	O
</s>
<s>
Some	O
manufacturers	O
and	O
retailers	O
incorrectly	O
market	O
SFX	O
power	O
supplies	O
as	O
μATX	B-Device
or	O
MicroATX	B-Device
power	O
supplies	O
.	O
</s>
<s>
Thin	O
Form	O
Factor	O
is	O
another	O
small	O
power	O
supply	O
design	O
with	O
standard	O
ATX	B-Architecture
specification	O
connectors	O
.	O
</s>
<s>
WTX	B-Device
power	O
supplies	O
provide	O
a	O
WTX	B-Device
style	O
motherboard	B-Device
connector	O
which	O
is	O
incompatible	O
with	O
the	O
standard	O
ATX	B-Architecture
motherboard	I-Architecture
connector	O
.	O
</s>
<s>
It	O
was	O
used	O
only	O
on	O
high-end	O
Athlon	O
MP	O
motherboards	B-Device
.	O
</s>
<s>
It	O
has	O
a	O
special	O
8-pin	O
supplemental	O
connector	O
for	O
motherboard	B-Device
,	O
so	O
an	O
AMD	O
GES	O
PSU	O
is	O
required	O
for	O
such	O
motherboards	B-Device
(	O
those	O
motherboards	B-Device
will	O
not	O
work	O
with	O
ATX(12V )	O
PSUs	O
)	O
.	O
</s>
<s>
a	O
.	O
ATX12V-GES	O
24-pin	O
P1	O
motherboard	B-Device
connector	O
.	O
</s>
<s>
The	O
pinout	O
on	O
the	O
motherboard	B-Device
connector	O
is	O
as	O
follows	O
when	O
viewing	O
the	O
motherboard	B-Device
from	O
above	O
:	O
</s>
<s>
b	O
.	O
ATX12V-GES	O
8-pin	O
P2	O
motherboard	B-Device
connector	O
.	O
</s>
<s>
This	O
pinout	O
on	O
the	O
motherboard	B-Device
connector	O
is	O
as	O
follows	O
when	O
viewing	O
the	O
motherboard	B-Device
from	O
above	O
:	O
</s>
<s>
EPS12V	O
is	O
defined	O
in	O
Server	O
System	O
Infrastructure	O
(	O
SSI	B-Device
)	O
and	O
used	O
primarily	O
by	O
SMP/multi	O
-core	O
systems	O
such	O
as	O
Core	B-Device
2	I-Device
,	O
Core	B-Device
i7	I-Device
,	O
Opteron	B-General_Concept
and	O
Xeon	B-Device
.	O
</s>
<s>
It	O
has	O
a	O
24-pin	O
ATX	B-Architecture
motherboard	I-Architecture
connector	O
(	O
same	O
as	O
ATX12V	O
v2.x	O
)	O
,	O
an	O
8-pin	O
secondary	O
connector	O
and	O
an	O
optional	O
4-pin	O
tertiary	O
connector	O
.	O
</s>
<s>
Rather	O
than	O
include	O
the	O
extra	O
cable	O
,	O
many	O
power	O
supply	O
makers	O
implement	O
the	O
8-pin	O
connector	O
as	O
two	O
combinable	O
4-pin	O
connectors	O
to	O
ensure	O
backwards	O
compatibility	O
with	O
ATX12V	O
motherboards	B-Device
.	O
</s>
<s>
High-performance	O
video	O
card	O
power	O
demands	O
dramatically	O
increased	O
during	O
the	O
2000s	O
and	O
some	O
high-end	O
graphics	O
cards	O
have	O
power	O
demands	O
that	O
exceed	O
AGP	B-Architecture
or	O
PCIe	O
slot	O
capabilities	O
.	O
</s>
<s>
Although	O
the	O
ATX	B-Architecture
power	O
supply	O
specifications	O
are	O
mostly	O
vertically	O
compatible	O
in	O
both	O
ways	O
(	O
both	O
electrically	O
and	O
physically	O
)	O
,	O
there	O
are	O
potential	O
issues	O
with	O
mixing	O
old	O
motherboards/systems	O
with	O
new	O
PSUs	O
and	O
vice	O
versa	O
.	O
</s>
<s>
The	O
power	O
allocation	O
between	O
3.3V	O
,	O
5V	O
and	O
12V	O
rails	O
is	O
very	O
different	O
between	O
older	O
and	O
newer	O
ATX	B-Architecture
PSU	O
designs	O
,	O
as	O
well	O
as	O
between	O
older	O
and	O
newer	O
PC	O
system	O
designs	O
.	O
</s>
<s>
Older	O
systems	O
(	O
before	O
Pentium4	B-General_Concept
and	O
AthlonXP	O
platforms	O
)	O
were	O
designed	O
to	O
draw	O
most	O
power	O
from	O
5V	O
and	O
3.3V	O
rails	O
.	O
</s>
<s>
Because	O
of	O
the	O
DC-DC	O
converters	O
on	O
the	O
motherboard	B-Device
that	O
convert	O
12V	O
to	O
the	O
low	O
voltages	O
required	O
by	O
the	O
Intel	B-General_Concept
Pentium	I-General_Concept
4	I-General_Concept
and	O
AMD	O
AthlonXP	O
(	O
and	O
subsequent	O
)	O
processors	O
,	O
such	O
systems	O
draw	O
most	O
of	O
their	O
power	O
from	O
the	O
12V	O
rail	O
.	O
</s>
<s>
Original	O
ATX	B-Architecture
PSUs	O
have	O
power	O
distribution	O
designed	O
for	O
pre-P4/XP	O
PCs	O
.	O
</s>
<s>
They	O
lack	O
the	O
supplemental	O
4-pin	O
12-volt	O
CPU	O
power	O
connector	O
,	O
so	O
they	O
most	O
likely	O
cannot	O
be	O
used	O
with	O
P4/XP	O
or	O
newer	O
motherboards	B-Device
.	O
</s>
<s>
It	O
is	O
not	O
recommended	O
to	O
use	O
ATX12V	O
1.x	O
PSUs	O
on	O
ATX12V	O
2.x	O
motherboards	B-Device
because	O
those	O
systems	O
require	O
much	O
more	O
power	O
on	O
12V	O
than	O
ATX12V	O
1.x	O
PSUs	O
provide	O
.	O
</s>
<s>
Systems	O
that	O
use	O
an	O
ISA	B-Architecture
bus	I-Architecture
should	O
have	O
a	O
PSU	O
that	O
provides	O
the	O
−5V	O
rail	O
,	O
which	O
became	O
optional	O
in	O
ATX12V	O
1.2	O
and	O
was	O
subsequently	O
phased	O
out	O
by	O
manufacturers	O
.	O
</s>
