MaximumPC 2008 11

60 | MAXIMUMPC | NOV 08 | http://www.maximumpc.com

CPU Tweaks

There’s more to prepping a rig for a new CPU than just setting the FSB

POWER STRUGGLE

If you’re used to poking around the BIOS, you

don’t need to be told that the CPU’s overall

clock speed is determined by multiplying the

CPU’s clock multiplier by the front-side bus. In

other words, the overall clock speed of a CPU

with an 8x multiplier and a front-side bus of

400 is 3200MHz.

What you might not know is the purpose

of some of the more obscure CPU-related BIOS

settings. Both C1E and EIST relate to power-

saving techniques employed by Intel CPUs.

EIST, or Enhanced Intel SpeedStep Technol-

ogy, is an off shoot of the notebook SpeedStep

feature that lowers the CPU speed when it’s

not under heavy use. C1E is an enhanced halt

state that cuts the clock multiplier in the CPU

to a preset value when the OS tells the chip

that it has no work for it. Each has pros and

cons. EIST is known for greater granularity,

ramping up and down depending on load,

but it does require driver support in the OS

to manage it. Critics say EIST can actually

reduce performance since it’s designed to

operate the CPU at lower speeds whenever it’s

not running at 100 percent capacity. The C1E

state is issued by the OS when it’s idle, so C1E

doesn’t require quite as much management.

But some overclockers prefer to disable C1E

since it can interfere with overclocks. We’ve

seen older boards feature settings for both, but

in our experience, newer chipsets from Intel

contain settings only for C1E. Flipping off the

features will force the CPU to always run at its

maximum clock speed. Phenoms have similar

features with Cool’n’Quiet (akin to EIST) and

now C1E support. While you’re not supposed

to, we’ve run with both settings on without

issues, but your mileage may vary.

New CPUs include thermal sensors that

slow down the CPU when it overheats. If you’d

rather have your machine bluescreen instead of

slow down (perhaps for stress testing), you can

switch CPU Thermal Control in the BIOS to Off.

NForce chipsets actually let you select between

lowering the CPU clock speed, or cutting the

multiplier and voltage, or both. Since we’d

rather lose performance than outright crash, we

normally set the BIOS so the clock speeds drop.

VIRTUALLY USELESS

One CPU setting that can probably be turned

off by most folks is VT, aka Vanderpool or

Virtualization support. The setting enables

virtualization hardware support in the CPU

for, well, virtualization. It basically turns on

the hardware “acceleration” capabilities

when using such applications as VMWare or

Virtual PC. If you don’t run virtualization, it’s

completely unnecessary. If you do, well, don’t

expect miracles since hardware acceleration of

virtualization is still in its early phases.

PROTECTIVE MEASURES

The Execute Disable option is a switch in the

BIOS that prevents many buffer overflow at-

tacks, whereby malicious programs are able

to circumvent security by putting viral code

in RAM and executing it

by intentionally over-

flowing the buffer. AMD

created the feature and

calls it NX. Intel’s clone

of it is called XD. Both do

the same thing. There’s

some disagreement

whether it hurts or helps

though. Some people

have reported problems

with overclocking when

Execute Disable is on,

while others claim it’s not

an issue.

Our take is to leave

it on unless you’re spe-

cifi cally having problems

with it—on the other

hand, we’re skeptical whether the feature

makes a lick of diff erence. If it did, wouldn’t

it make Windows XP SP2 machines totally

secure? Right.

To verify that hardware data execution

protection is enabled, go into Windows, hit

Start, then Run, and type CMD. Enter the

command wmic OS Get DataExecu-

tionPrevention_Available. The re-

sponse should be “true.” Or simply download

Gibson Research’s SecurAble (www.grc

.com/securable.htm), which will scan your

machine to verify protection.

Some overclockers prefer to turn off virtualization support—not a bad idea if you don’t run any vitual-

ization software.

OLD TECH, NEW TWEAKS

This BIOS has Execute Disable technology as well as Enhanced Intel

SpeedStep and C1E enabled.