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STRESS TESTING YOUR COMPUTER

BACKGROUND

Today’s computers are not perfect. Even brand new systems from major

manufacturers can have hidden flaws. If any of several key components such

as CPU, memory, cooling, etc. are not up to spec, it can lead to incorrect

calculations and/or unexplained system crashes.

Overclocking is the practice of increasing the speed of the CPU and/or

memory to make a machine faster at little cost. Typically, overclocking

involves pushing a machine past its limits and then backing off just a

little bit.

For these reasons, both non-overclockers and overclockers need programs

that test the stability of their computers. This is done by running

programs that put a heavy load on the computer. Though not originally

designed for this purpose, this program is one of a few programs that

are excellent at stress testing a computer.

RESOURCES

This program is a good stress test for the CPU, memory, L1 and L2 caches,

CPU cooling, and case cooling. The torture test runs continuously, comparing

your computer’s results to results that are known to be correct. Any

mismatch and you’ve got a problem! Note that the torture test sometimes

reads from and writes to disk but cannot be considered a stress test for

hard drives.

You’ll need other programs to stress video cards, PCI bus, disk access,

networking and other important components. In addition, this is only one

of several good programs that are freely available. Some people report

finding problems only when running two or more stress test programs

concurrently. You may need to raise prime95’s priority when running two

stress test programs so that each gets about 50% of the CPU time.

Forums are a great place to learn about available stability test programs

and to get advice on what to do when a problem is found.

The currently popular stability test programs are (sorry, I don’t have

web addresses for these):

Prime95 (this program’s torture test)

3DMark2001

CPU Stability test

Sisoft sandra

Quake and other games

Folding@Home

Seti@home

Genome@home

Several useful websites for help (look for overclocking community or forum):

http://www.overclockers.com

http://www.arstechnica.com

http://www.hardocp.com

http://www.anandtech.com

http://www.tomshardware.com

http://www.sharkyextreme.com

Also try the alt.comp.hardware.overclocking Usenet newsgroup.

Utility programs you may find useful (I’m sure there are others – look around):

Motherboard monitor from http://mbm.livewiredev.com

Memtest86 from http://www.memtest86.com

Cpuburn by redelm: http://pages.sbcglobal.net/redelm/

TaskInfo2002 from http://www.iarsn.com/

WHAT TO DO IF A PROBLEM IS FOUND?

The exact cause of a hardware problem can be very hard to find.

If you are not overclocking, the most likely cause is an overheating CPU

or memory DIMMs that are not quite up to spec. Another possibility is

you might need a better power supply. Try running MotherBoard monitor

and browse the forums above to see if your CPU is running too hot.

If so, make sure the heat sink is properly attached, fans are operational,

and air flow inside the case is good. For isolating memory problems, try

swapping memory DIMMs with a co-worker’s or friend’s machine. If the errors

go away, then you can be fairly confidant that memory was the cause of

the trouble. A power supply problem can often be identified by a significant

drop in the voltages when prime95 starts running. Once again the overclocker

forums are a good resource for what voltages are acceptable.

If you are overclocking then try increasing the core voltage, reduce the

CPU speed, reduce the front side bus speed, or change the memory timings

(CAS latency). Also try asking for help in one of the forums above – they

may have other ideas to try.

CAN I IGNORE THE PROBLEM?

Ignoring the problem is a matter of personal preference. There are

two schools of thought on this subject.

Most programs you run will not stress your computer enough to cause a

wrong result or system crash. If you ignore the problem, then video games

may stress your machine resulting in a system crash. Also, stay away from

distributed computing projects where an incorrect calculation might cause

you to return wrong results. Bad data will not help these projects!

In conclusion, if you are comfortable with a small risk of an occasional

system crash then feel free to live a little dangerously! Keep in mind

that the faster prime95 finds a hardware error the more likely it is that

other programs will experience problems.

The second school of thought is, “Why run a stress test if you are going

to ignore the results?” These people want a guaranteed 100% rock solid

machine. Passing these stability tests gives them the ability to run

CPU intensive programs with confidence.

FREQUENTLY ASKED QUESTIONS

Q) My machine is not overclocked. If I’m getting an error, then there must

be a bug in the program, right?

A) The torture test is comparing your machines results against

KNOWN CORRECT RESULTS. If your machine cannot generate correct

results, you have a hardware problem. HOWEVER, if you are failing

the torture test in the SAME SPOT with the SAME ERROR MESSAGE

every time, then ask for help at http://mersenneforum.org – it is

possible that a recent change to the torture test code may have

introduced a software bug.

Q) How long should I run the torture test?

A) I recommend running it for somewhere between 6 and 24 hours.

The program has been known to fail only after several hours and in

some cases several weeks of operation. In most cases though, it will

fail within a few minutes on a flaky machine.

Q) Prime95 reports errors during the torture test, but other stability

tests don’t. Do I have a problem?

A) Yes, you’ve reached the point where your machine has been

pushed just beyond its limits. Follow the recommendations above

to make your machine 100% stable or decide to live with a

machine that could have problems in rare circumstances.

Q) A forum member said “Don’t bother with prime95, it always pukes on me,

and my system is stable!. What do you make of that?”

or

“We had a server at work that ran for 2 MONTHS straight, without a reboot

I installed Prime95 on it and ran it – a couple minutes later I get an error.

You are going to tell me that the server wasn’t stable?”

A) These users obviously do not subscribe to the 100% rock solid

school of thought. THEIR MACHINES DO HAVE HARDWARE PROBLEMS.

But since they are not presently running any programs that reveal

the hardware problem, the machines are quite stable. As long as

these machines never run a program that uncovers the hardware problem,

then the machines will continue to be stable.

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