<s>
The	O
CPU	B-Device
core	I-Device
voltage	I-Device
(	O
VCORE	B-Device
)	O
is	O
the	O
power	O
supply	O
voltage	O
supplied	O
to	O
the	O
CPU	B-Device
(	O
which	O
is	O
a	O
digital	O
circuit	O
)	O
,	O
GPU	B-Architecture
,	O
or	O
other	O
device	O
containing	O
a	O
processing	O
core	O
.	O
</s>
<s>
The	O
amount	O
of	O
power	O
a	O
CPU	B-Device
uses	O
,	O
and	O
thus	O
the	O
amount	O
of	O
heat	O
it	O
dissipates	O
,	O
is	O
the	O
product	O
of	O
this	O
voltage	O
and	O
the	O
current	O
it	O
draws	O
.	O
</s>
<s>
In	O
modern	O
CPUs	B-Device
,	O
which	O
are	O
CMOS	B-Device
circuits	O
,	O
the	O
current	O
is	O
almost	O
proportional	O
to	O
the	O
clock	O
speed	O
,	O
the	O
CPU	B-Device
drawing	O
almost	O
no	O
current	O
between	O
clock	O
cycles	O
.	O
</s>
<s>
To	O
conserve	O
power	O
and	O
manage	O
heat	O
,	O
many	O
laptop	B-Device
and	O
desktop	B-Device
processors	O
have	O
a	O
power	O
management	O
feature	O
that	O
software	O
(	O
usually	O
the	O
operating	B-General_Concept
system	I-General_Concept
)	O
can	O
use	O
to	O
adjust	O
the	O
clock	O
speed	O
and	O
core	B-Device
voltage	I-Device
dynamically	O
.	O
</s>
<s>
Often	O
a	O
voltage	O
regulator	O
module	O
converts	O
from	O
5V	O
or	O
12	O
V	O
or	O
some	O
other	O
voltage	O
to	O
whatever	O
CPU	B-Device
core	I-Device
voltage	I-Device
is	O
required	O
by	O
the	O
CPU	B-Device
.	O
</s>
<s>
The	O
trend	O
is	O
towards	O
lower	O
core	B-Device
voltages	I-Device
,	O
which	O
conserve	O
power	O
.	O
</s>
<s>
This	O
presents	O
the	O
CMOS	B-Device
designer	O
with	O
a	O
challenge	O
,	O
because	O
in	O
CMOS	B-Device
the	O
voltages	O
go	O
only	O
to	O
ground	O
and	O
the	O
supply	O
voltage	O
,	O
the	O
source	O
,	O
gate	O
,	O
and	O
drain	O
terminals	O
of	O
the	O
FETs	O
have	O
only	O
the	O
supply	O
voltage	O
or	O
zero	O
voltage	O
across	O
them	O
.	O
</s>
<s>
The	O
MOSFET	B-Architecture
formula	O
:	O
says	O
that	O
the	O
current	O
supplied	O
by	O
the	O
FET	O
is	O
proportional	O
to	O
the	O
gate-source	O
voltage	O
reduced	O
by	O
a	O
threshold	O
voltage	O
,	O
which	O
depends	O
on	O
the	O
geometrical	O
shape	O
of	O
the	O
FET	O
's	O
channel	O
and	O
gate	O
and	O
their	O
physical	O
properties	O
,	O
especially	O
capacitance	O
.	O
</s>
<s>
Only	O
improvements	O
in	O
photolithography	B-Algorithm
and	O
reduction	O
in	O
threshold	O
voltage	O
allow	O
both	O
to	O
improve	O
at	O
once	O
.	O
</s>
<s>
On	O
another	O
note	O
,	O
the	O
formula	O
shown	O
above	O
is	O
for	O
long	O
channel	O
MOSFETs	B-Architecture
.	O
</s>
<s>
With	O
the	O
area	O
of	O
the	O
MOSFETs	B-Architecture
halving	O
every	O
18-24	O
months	O
(	O
Moore	O
's	O
law	O
)	O
the	O
distance	O
between	O
the	O
two	O
terminals	O
of	O
the	O
MOSFET	B-Architecture
switch	O
called	O
the	O
channel	O
length	O
is	O
becoming	O
smaller	O
and	O
smaller	O
.	O
</s>
<s>
Overclocking	B-Application
a	O
processor	O
increases	O
its	O
clock	O
speed	O
at	O
the	O
cost	O
of	O
system	O
stability	O
.	O
</s>
<s>
Withstanding	O
higher	O
clock	O
speeds	O
often	O
requires	O
higher	O
core	B-Device
voltage	I-Device
at	O
the	O
cost	O
of	O
power	O
consumption	O
and	O
heat	O
dissipation	O
.	O
</s>
<s>
Overvolting	O
generally	O
involves	O
running	O
a	O
processor	O
out	O
of	O
its	O
specifications	O
,	O
which	O
may	O
damage	O
it	O
or	O
shorten	O
CPU	B-Device
life	O
.	O
</s>
<s>
A	O
dual-voltage	O
CPU	B-Device
uses	O
a	O
split-rail	O
design	O
so	O
the	O
processor	O
core	O
can	O
use	O
a	O
lower	O
voltage	O
,	O
while	O
the	O
external	O
Input/Output	B-General_Concept
(	O
I/O	B-General_Concept
)	O
voltages	O
remain	O
at	O
3.3	O
volts	O
for	O
backwards	O
compatibility	O
.	O
</s>
<s>
A	O
single-voltage	O
CPU	B-Device
uses	O
a	O
single	O
power	O
voltage	O
throughout	O
the	O
chip	O
,	O
supplying	O
both	O
I/O	B-General_Concept
power	O
and	O
internal	O
power	O
.	O
</s>
<s>
As	O
of	O
2002	O
Microprocessor	O
#Market	O
statistics	O
,	O
most	O
CPUs	B-Device
are	O
single-voltage	O
CPUs	B-Device
.	O
</s>
<s>
All	O
CPUs	B-Device
before	O
the	O
Pentium	B-Device
MMX	O
are	O
single-voltage	O
CPUs	B-Device
.	O
</s>
<s>
Dual-voltage	O
CPUs	B-Device
were	O
introduced	O
for	O
performance	O
gain	O
when	O
increasing	O
clock	O
speeds	O
and	O
finer	O
semiconductor	B-Architecture
fabrication	I-Architecture
processes	O
caused	O
excess	O
heat	O
generation	O
and	O
power	O
supply	O
concerns	O
,	O
especially	O
regarding	O
laptop	B-Device
computers	I-Device
.	O
</s>
<s>
Using	O
a	O
voltage	O
regulator	O
,	O
the	O
external	O
I/O	B-General_Concept
voltage	O
levels	O
was	O
transformed	O
to	O
lower	O
voltages	O
to	O
reduce	O
power	O
draw	O
,	O
resulting	O
in	O
less	O
heat	O
for	O
the	O
ability	O
to	O
operate	O
at	O
higher	O
frequencies	O
.	O
</s>
<s>
VRT	O
is	O
a	O
feature	O
on	O
older	O
Intel	B-General_Concept
P5	I-General_Concept
Pentium	B-Device
processors	I-Device
that	O
are	O
typically	O
intended	O
for	O
use	O
in	O
a	O
mobile	O
environment	O
.	O
</s>
<s>
It	O
refers	O
to	O
splitting	O
the	O
core	B-Device
voltage	I-Device
supply	O
from	O
the	O
I/O	B-General_Concept
voltage	O
.	O
</s>
<s>
A	O
VRT	O
processor	O
has	O
a	O
3.3	O
V	O
I/O	B-General_Concept
and	O
2.9	O
V	O
core	B-Device
voltage	I-Device
,	O
to	O
save	O
power	O
compared	O
to	O
a	O
typical	O
Pentium	B-Device
processor	I-Device
with	O
both	O
I/O	B-General_Concept
and	O
core	B-Device
voltage	I-Device
at	O
3.3V	O
.	O
</s>
<s>
All	O
Pentium	B-Device
MMX	O
and	O
later	O
processors	O
adopted	O
this	O
so-called	O
split	O
rail	O
power	O
supply	O
.	O
</s>
