<s>
GPU	B-Device
switching	I-Device
is	O
a	O
mechanism	O
used	O
on	O
computers	O
with	O
multiple	O
graphic	B-Architecture
controllers	I-Architecture
.	O
</s>
<s>
Most	O
computers	O
using	O
this	O
feature	O
contain	O
integrated	O
graphics	B-Architecture
processors	I-Architecture
and	O
dedicated	O
graphics	O
cards	O
that	O
applies	O
to	O
the	O
following	O
categories	O
.	O
</s>
<s>
Also	O
known	O
as	O
:	O
Integrated	O
graphics	O
,	O
shared	O
graphics	O
solutions	O
,	O
integrated	O
graphics	B-Architecture
processors	I-Architecture
(	O
IGP	O
)	O
or	O
unified	O
memory	O
architecture	O
(	O
UMA	O
)	O
.	O
</s>
<s>
This	O
kind	O
of	O
graphics	B-Architecture
processors	I-Architecture
usually	O
have	O
much	O
fewer	O
processing	O
units	O
and	O
share	O
the	O
same	O
memory	O
with	O
the	O
CPU	B-General_Concept
.	O
</s>
<s>
Sometimes	O
the	O
graphics	B-Architecture
processors	I-Architecture
are	O
integrated	O
onto	O
a	O
motherboard	B-Device
.	O
</s>
<s>
A	O
motherboard	B-Device
with	O
on-board	O
graphics	B-Architecture
processors	I-Architecture
does	O
n't	O
require	O
a	O
discrete	O
graphics	O
card	O
or	O
a	O
CPU	B-General_Concept
with	O
graphics	B-Architecture
processors	I-Architecture
to	O
operate	O
.	O
</s>
<s>
Unlike	O
integrated	O
graphics	O
,	O
dedicated	O
graphics	O
cards	O
have	O
much	O
more	O
processing	O
units	O
and	O
have	O
its	O
own	O
RAM	B-Architecture
with	O
much	O
higher	O
memory	O
bandwidth	O
.	O
</s>
<s>
In	O
some	O
cases	O
,	O
a	O
dedicated	O
graphics	O
chip	O
can	O
be	O
integrated	O
onto	O
the	O
motherboards	B-Device
,	O
B150-GP104	O
for	O
example	O
.	O
</s>
<s>
Most	O
Personal	B-Device
Computers	I-Device
have	O
a	O
motherboard	B-Device
that	O
uses	O
a	O
Southbridge	B-Device
and	O
Northbridge	B-Device
structure	O
.	O
</s>
<s>
The	O
Northbridge	B-Device
is	O
one	O
of	O
the	O
core	O
logic	O
chipset	B-Device
that	O
handles	O
communications	O
between	O
the	O
CPU	B-General_Concept
,	O
GPU	B-Architecture
,	O
RAM	B-Architecture
and	O
the	O
Southbridge	B-Device
.	O
</s>
<s>
The	O
discrete	O
graphics	O
card	O
is	O
usually	O
installed	O
onto	O
the	O
graphics	O
card	O
slot	O
such	O
as	O
PCI-Express	O
and	O
the	O
integrated	O
graphics	O
is	O
integrated	O
onto	O
the	O
CPU	B-General_Concept
itself	O
or	O
occasionally	O
onto	O
the	O
Northbridge	B-Device
.	O
</s>
<s>
The	O
Northbridge	B-Device
is	O
the	O
most	O
responsible	O
for	O
switching	O
between	O
GPUs	B-Architecture
.	O
</s>
<s>
The	O
Northbridge	B-Device
receives	O
input	O
from	O
Southbridge	B-Device
through	O
the	O
internal	O
bus	O
.	O
</s>
<s>
The	O
Northbridge	B-Device
signals	O
to	O
CPU	B-General_Concept
through	O
the	O
Front-side	O
bus	O
.	O
</s>
<s>
The	O
CPU	B-General_Concept
runs	O
the	O
task	O
assignment	O
application	O
(	O
usually	O
the	O
graphics	O
card	O
driver	O
)	O
to	O
determine	O
which	O
GPU	B-Architecture
core	O
to	O
use	O
.	O
</s>
<s>
The	O
CPU	B-General_Concept
passes	O
down	O
the	O
command	O
to	O
the	O
Northbridge	B-Device
.	O
</s>
<s>
The	O
Northbridge	B-Device
passes	O
down	O
the	O
command	O
to	O
the	O
according	O
GPU	B-Architecture
core	O
.	O
</s>
<s>
The	O
GPU	B-Architecture
core	O
processes	O
the	O
command	O
and	O
returns	O
the	O
rendered	O
data	O
back	O
to	O
the	O
Northbridge	B-Device
.	O
</s>
<s>
The	O
Northbridge	B-Device
sends	O
the	O
rendered	O
data	O
back	O
to	O
Southbridge	B-Device
.	O
</s>
<s>
The	O
Southbridge	B-Device
is	O
a	O
set	O
of	O
integrated	O
circuits	O
such	O
Intel	O
's	O
I/O	B-Device
Controller	I-Device
Hub	I-Device
(	O
ICH	O
)	O
.	O
</s>
<s>
Take	O
in	O
the	O
user	O
input	O
and	O
pass	O
it	O
down	O
to	O
the	O
Northbridge	B-Device
.	O
</s>
<s>
(	O
Optional	O
)	O
Receive	O
the	O
rendered	O
data	O
from	O
the	O
Northbridge	B-Device
and	O
output	O
it	O
.	O
</s>
<s>
The	O
reason	O
why	O
the	O
second	O
step	O
can	O
be	O
optional	O
is	O
that	O
sometimes	O
the	O
rendered	O
the	O
data	O
is	O
outputted	O
directly	O
from	O
the	O
discrete	O
graphics	O
card	O
which	O
is	O
located	O
on	O
the	O
graphics	O
card	O
slot	O
so	O
there	O
is	O
no	O
need	O
to	O
output	O
the	O
data	O
through	O
the	O
Southbridge	B-Device
.	O
</s>
<s>
GPU	B-Device
switching	I-Device
is	O
mostly	O
used	O
for	O
saving	O
energy	O
by	O
switching	O
between	O
graphic	O
cards	O
.	O
</s>
<s>
Following	O
is	O
a	O
list	O
of	O
the	O
TDPs	B-General_Concept
of	O
the	O
most	O
popular	O
CPU	B-General_Concept
with	O
integrated	O
graphics	O
and	O
dedicated	O
graphics	O
cards	O
.	O
</s>
<s>
Nvidia	O
Optimus™	O
is	O
a	O
computer	O
GPU	B-Device
switching	I-Device
technology	O
created	O
by	O
Nvidia	O
that	O
can	O
dynamically	O
and	O
seamlessly	O
switch	O
between	O
two	O
graphic	O
cards	O
based	O
on	O
running	O
programs	O
.	O
</s>
<s>
In	O
personal	B-Device
computers	I-Device
,	O
the	O
IGP	O
(	O
integrated	O
graphics	B-Architecture
processors	I-Architecture
)	O
are	O
mostly	O
manufactured	O
by	O
Intel	O
and	O
AMD	O
and	O
are	O
integrated	O
onto	O
their	O
CPUs	B-General_Concept
.	O
</s>
<s>
Most	O
common	O
operating	B-General_Concept
systems	I-General_Concept
have	O
built-in	O
support	O
for	O
this	O
feature	O
.	O
</s>
<s>
Windows	B-Device
7	I-Device
has	O
built-in	O
support	O
for	O
this	O
feature	O
.	O
</s>
<s>
The	O
system	O
automatically	O
switches	O
between	O
GPUs	B-Architecture
depending	O
on	O
the	O
program	O
that	O
's	O
running	O
.	O
</s>
<s>
However	O
,	O
the	O
user	O
may	O
switch	O
the	O
GPUs	B-Architecture
manually	O
through	O
device	O
manager	O
or	O
power	O
manager	O
.	O
</s>
<s>
In	O
the	O
Linux	B-Operating_System
systems	O
,	O
a	O
patch	O
named	O
vga_switcheroo	O
has	O
been	O
added	O
to	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
since	O
version	O
2.6.34	O
in	O
order	O
to	O
deal	O
with	O
multiple	O
GPUs	B-Architecture
.	O
</s>
<s>
Here	O
,	O
the	O
switch	O
requires	O
a	O
restart	O
of	O
the	O
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
to	O
be	O
taken	O
into	O
account	O
.	O
</s>
<s>
allows	O
the	O
user	O
to	O
access	O
vga_switcheroo	O
functionality	O
through	O
a	O
GUI	B-Application
.	O
</s>
<s>
Since	O
OS	B-Operating_System
X	I-Operating_System
Mountain	I-Operating_System
Lion	I-Operating_System
,	O
Apple	O
has	O
integrated	O
the	O
GPU	B-Architecture
monitor	O
into	O
the	O
Activity	O
Monitor	O
.	O
</s>
