<s>
Enhanced	O
SpeedStep	B-Device
is	O
a	O
series	O
of	O
dynamic	B-General_Concept
frequency	I-General_Concept
scaling	I-General_Concept
technologies	O
(	O
codenamed	O
Geyserville	O
and	O
including	O
SpeedStep	B-Device
,	O
SpeedStep	B-Device
II	O
,	O
and	O
SpeedStep	B-Device
III	O
)	O
built	O
into	O
some	O
Intel	O
microprocessors	B-Architecture
that	O
allow	O
the	O
clock	O
speed	O
of	O
the	O
processor	O
to	O
be	O
dynamically	O
changed	O
(	O
to	O
different	O
P-states	O
)	O
by	O
software	O
.	O
</s>
<s>
This	O
allows	O
the	O
processor	O
to	O
meet	O
the	O
instantaneous	O
performance	O
needs	O
of	O
the	O
operation	O
being	O
performed	O
,	O
while	O
minimizing	O
power	B-General_Concept
draw	I-General_Concept
and	I-General_Concept
heat	I-General_Concept
generation	I-General_Concept
.	O
</s>
<s>
EIST	B-Device
(	O
SpeedStep	B-Device
III	O
)	O
was	O
introduced	O
in	O
several	O
Prescott	O
6	O
series	O
in	O
the	O
first	O
quarter	O
of	O
2005	O
,	O
namely	O
the	O
Pentium	B-General_Concept
4	I-General_Concept
660	O
.	O
</s>
<s>
Intel	O
Speed	O
Shift	O
Technology	O
(	O
SST	O
)	O
was	O
introduced	O
in	O
Intel	B-Architecture
Skylake	I-Architecture
Processor	O
.	O
</s>
<s>
Enhanced	O
Intel	B-Device
SpeedStep	I-Device
Technology	O
is	O
sometimes	O
abbreviated	O
as	O
EIST	B-Device
.	O
</s>
<s>
Intel	O
's	O
trademark	O
of	O
"	O
INTEL	B-Device
SPEEDSTEP	I-Device
"	O
was	O
cancelled	O
due	O
to	O
the	O
trademark	O
being	O
invalidated	O
in	O
2012	O
.	O
</s>
<s>
In	O
many	O
cases	O
,	O
the	O
core	B-Device
voltage	I-Device
can	O
also	O
be	O
reduced	O
,	O
further	O
reducing	O
power	O
consumption	O
and	O
heat	O
generation	O
.	O
</s>
<s>
By	O
using	O
SpeedStep	B-Device
,	O
users	O
can	O
select	O
the	O
balance	O
of	O
power	O
conservation	O
and	O
performance	O
that	O
best	O
suits	O
them	O
,	O
or	O
even	O
change	O
the	O
clock	O
speed	O
dynamically	O
as	O
the	O
processor	O
burden	O
changes	O
.	O
</s>
<s>
For	O
example	O
,	O
for	O
a	O
1.6GHz	O
Pentium	B-Architecture
M	I-Architecture
,	O
the	O
clock	O
frequency	O
can	O
be	O
stepped	O
down	O
in	O
200MHz	O
decrements	O
over	O
the	O
range	O
from	O
1.6	O
to	O
0.6GHz	O
.	O
</s>
<s>
For	O
example	O
,	O
when	O
an	O
operating	O
system	O
is	O
not	O
busy	O
,	O
it	O
tends	O
to	O
issue	O
x86	B-Operating_System
halt	O
(	O
HLT	B-Language
)	O
instructions	O
,	O
which	O
suspend	O
operation	O
of	O
parts	O
of	O
the	O
CPU	O
for	O
a	O
time	O
period	O
,	O
so	O
it	O
uses	O
less	O
energy	O
per	O
tick	O
of	O
the	O
CPU	O
clock	O
than	O
when	O
executing	O
productive	O
instructions	O
in	O
its	O
normal	O
state	O
.	O
</s>
<s>
For	O
a	O
given	O
rate	O
of	O
work	O
,	O
a	O
CPU	O
running	O
at	O
a	O
higher	O
clock	O
rate	O
will	O
execute	O
a	O
greater	O
proportion	O
of	O
HLT	B-Language
instructions	I-Language
.	O
</s>
<s>
Older	O
processors	O
such	O
as	O
the	O
Pentium	O
4-M	O
,	O
which	O
use	O
older	O
versions	O
of	O
SpeedStep	B-Device
,	O
have	O
fewer	O
clock-speed	O
increments	O
.	O
</s>
<s>
SpeedStep	B-Device
technology	O
is	O
partly	O
responsible	O
for	O
the	O
reduced	O
power	O
consumption	O
of	O
Intel	O
's	O
Pentium	B-Architecture
M	I-Architecture
processor	O
,	O
part	O
of	O
the	O
Centrino	B-Device
brand	O
.	O
</s>
<s>
Microsoft	O
has	O
reported	O
that	O
there	O
may	O
be	O
problems	O
previewing	O
video	O
files	O
when	O
SpeedStep	B-Device
(	O
or	O
the	O
AMD	O
equivalent	O
PowerNow	B-Device
!	I-Device
)	O
</s>
<s>
is	O
enabled	O
under	O
Windows	B-Application
2000	I-Application
or	O
Windows	B-Application
XP	I-Application
.	O
</s>
<s>
Solaris	B-Application
has	O
supported	O
SpeedStep	B-Device
since	O
OpenSolaris	B-Operating_System
SXDE	O
9/07	O
.	O
</s>
<s>
Older	O
versions	O
of	O
Microsoft	O
Windows	O
,	O
Windows	B-Application
2000	I-Application
and	O
earlier	O
,	O
need	O
a	O
special	O
driver	O
and	O
dashboard	O
application	O
to	O
access	O
the	O
SpeedStep	B-Device
feature	O
.	O
</s>
<s>
Intel	O
's	O
website	O
specifically	O
states	O
that	O
such	O
drivers	O
must	O
come	O
from	O
the	O
computer	O
manufacturer	O
;	O
there	O
are	O
no	O
generic	O
drivers	O
supplied	O
by	O
Intel	O
which	O
will	O
enable	O
SpeedStep	B-Device
for	O
older	O
Windows	O
versions	O
if	O
one	O
cannot	O
obtain	O
a	O
manufacturer	O
's	O
driver	O
.	O
</s>
<s>
Under	O
Microsoft	B-Application
Windows	I-Application
XP	I-Application
,	O
SpeedStep	B-Device
support	O
is	O
built	O
into	O
the	O
power	O
management	O
console	O
under	O
the	O
control	O
panel	O
.	O
</s>
<s>
In	O
Windows	B-Application
XP	I-Application
a	O
user	O
can	O
regulate	O
processor	O
speed	O
indirectly	O
by	O
changing	O
power	O
schemes	O
.	O
</s>
<s>
The	O
"	O
Home/Office	O
Desk	O
"	O
setting	O
disables	O
SpeedStep	B-Device
,	O
the	O
"	O
Portable/Laptop	O
"	O
power	O
scheme	O
enables	O
SpeedStep	B-Device
,	O
and	O
the	O
"	O
Max	O
Battery	O
"	O
uses	O
SpeedStep	B-Device
to	O
slow	O
the	O
processor	O
to	O
minimal	O
power	O
levels	O
as	O
the	O
battery	O
weakens	O
.	O
</s>
<s>
The	O
SpeedStep	B-Device
settings	O
for	O
power	O
schemes	O
,	O
either	O
built-in	O
or	O
custom	O
,	O
cannot	O
be	O
modified	O
from	O
the	O
control	O
panel	O
's	O
GUI	O
,	O
but	O
can	O
be	O
modified	O
using	O
the	O
POWERCFG.EXE	O
command-line	O
utility	O
.	O
</s>
<s>
The	O
Linux	B-Operating_System
kernel	I-Operating_System
has	O
a	O
subsystem	O
called	O
"	O
cpufreq	O
"	O
,	O
tunable	O
by	O
power-scheme	O
and	O
command	O
line	O
,	O
devoted	O
to	O
the	O
control	O
of	O
the	O
operating	O
frequency	O
and	O
voltage	O
of	O
a	O
CPU	O
.	O
</s>
<s>
Linux	B-Operating_System
runs	O
on	O
Intel	O
,	O
AMD	O
,	O
and	O
other	O
makes	O
of	O
CPU	O
.	O
</s>
<s>
Newer	O
version	O
Windows	B-Operating_System
10	I-Operating_System
and	O
Linux	B-Operating_System
kernel	I-Operating_System
support	O
Intel	O
Speed	O
Shift	O
Technology	O
.	O
</s>
<s>
In	O
contrast	O
,	O
AMD	O
has	O
supplied	O
and	O
supported	O
drivers	O
for	O
its	O
competing	O
PowerNow	B-Device
!	I-Device
</s>
<s>
technology	O
that	O
work	O
on	O
Windows	B-Application
2000	I-Application
,	O
ME	O
,	O
98	O
,	O
and	O
NT	O
.	O
</s>
