Hyperthreading, Overclocking, and Prime95.

[aggressor]

How many of you with P4Cs run 2 instances of Prime95 (-a2 switch) with HT on to max out the CPU? This seems like it would be the best CPU stress testing for overclocking.

Example: I have a 2.4c. I can run 2 instances of Prime95 at default stock without a problem. When I turn it up to 3.2ghz, 2 instances will freeze me within 2 minutes. Disabling HT lets me run for much longer. Does this make my machine unstable only in programs which 'use' Hyperthreading?

 

[aggressor]

No opinions on this?

 

[oldfart]

I didn't know about the switch. Thanks! I ran two instances by running 2 different versions. I also have Serious Sam looping at the same time to really stress things when testing.

 

[aggressor]

So with HT systems, dual Prime95 is the only way to go to test stability?

 

[Overkiller]

It would make sense b/c otherwise only 50% would be used in case there was another trace program. so it would be 50% on one and like 2 % on another program. 2 instances of prime is prolly a sweet spot. and leave HT on i would say..but that's just me

 

[AnImuS]

Originally posted by: aggressor
So with HT systems, dual Prime95 is the only way to go to test stability?

You can try SETI@Home Or Folding@Home to stress the system...

 

[oldfart]

Am I doing it wrong? I launch via the run command like this
"D:\Program Files\Prime95\Prime95.exe" -a2
or via a command prompt like this
D:\Program Files\Prime95>prime95.exe -a2
And I only get one instance. CPU ulil is not 100%.

What am I doing wrong?

 

[aggressor]

Overkiller:
Yes, if HT is enabled, Prime95 will only use 1 Logical CPU for 50% total, but when HT is disabled, the CPU Usage is at 100% with only one instance of Prime95 running.

oldfart:
I launch one the regular way and the second with the -a2 switch

 

[oldfart]

Ahh....got it now.

Thanks!

BTW, how much mem do you allocate for each? What is the best stress test?

 

[aggressor]

With 1gb of ram, I assign each one 450mb