Prime95: question on testing for stability

[Flakk]

When I run Prime95 on my computer with a 2.4C, it uses only half the CPU utilization (about 1/3rds in the cpu 0 and 2/3rds in cpu 0, averaging 50% load). Is this normal? Why does it only use 50% when it's stress testing the system...

I run Seti @ Home now in conjunction with Prime95 when doing a torture test and this keeps it at a steady 100% utilization. Does anyone else do this? Is it a good idea?

Also, when running the torture test, there are 3 options:
- Small FFTs
- In-place Large FFTs
- Blend

Is there 1 that is recommended to use for overall system stability (cpu and ram).. "Blend" mode? Or should I run all of them. What do you veterans do?

Also oddly, now that I have a CPU with hyperthreading.. my Seti@Home only uses 50% when run alone. On my 2.4b it used 100% all the time. I have to run two of them to get 100% cpu utilization.

 

[NookieN]

Seeing 50% utilization when you're running one program on an HT-enabled processor is normal. It _does_not_ mean you're only using 50% of the power of the cpu. It's just poor design in Windows' task manager (it thinks you have two physical cpus, which of course is not the case).

For overall system stability testing, Blend is best. There's nothing wrong with running both Seti and Prime at the same time, although they will both run slower. I think it's usually best to make sure Prime runs ok by itself before I start running it in parallel with another program.

 

[Cyrix_2k]

It might also be that you set your priorty rating too low. It should be set around 10, I think.

 

[Flakk]

I think it's usually best to make sure Prime runs ok by itself before I start running it in parallel with another program.

meaning, you think that running it in parallel with another program is more strenuous a test? Well that is exactly what i want

-edit-
altho, if the 50% utilization is really 100%, then perhaps prime alone is better and faster as u said...

 

[zabomb4163]

altho, if the 50% utilization is really 100%, then perhaps prime alone is better and faster as u said...

no.....i get 5C higher temps running 2 programs than just prime. i prefer running pifast and prime95 with cpu affinity set at 2.

 

[Hoot]

Go into the advanced menu, set the password to 9876, then you can set priority to 10 instead of 1. Believe me, it will run that CPU at 100% or darned close and with it utilizing all that the CPU has to offer, you won't need to run anything else. Priority 10 is what separates the bogus overclocks from the truly stable ones.

Hoot

 

[zabomb4163]

thanks hoot, i didn't know about that feature.

 

[Zyl]

I had heard, that for HT processors, to really stress the CPU, you run two instances of prime. Load up 1 instance, then set the cpu affinity to cpu 0, and set priority in task manager to realtime? i think. Then load up the 2nd instance of prime and then set cpu affinity for the 2nd prime on cpu1 and change its priority as well. I am sure this works for duallies but i also heard that it works for intels with hyper-threading. Good lucks!

 

[zabomb4163]

Go into the advanced menu, set the password to 9876, then you can set priority to 10 instead of 1. Believe me, it will run that CPU at 100% or darned close and with it utilizing all that the CPU has to offer, you won't need to run anything else. Priority 10 is what separates the bogus overclocks from the truly stable ones.

Hoot

unforuntaly.......runing prime affinity set at 2 and pifast at the the same time yields 4C higher temps than just runing prime with priority to 10.

 

[Flakk]

how do u change the priority on a numerical scale.. i can only set between: RealTime, High, AboveNormal, Normal, BelowNormal, Low

 

[Hoot]

unforuntaly.......runing prime affinity set at 2 and pifast at the the same time yields 4C higher temps than just runing prime with priority to 10.

I will check that out on my machine tonight. To date, the only thing I've found that runs the CPU hotter than priority 10 was a DOS app called BurnK7 used with a small app that gives it a high priority under DOS, I forget the name or the priority program you run first.

Originally posted by Flakk


how do u change the priority on a numerical scale.. i can only set between: RealTime, High, AboveNormal, Normal, BelowNormal, Low

You don't set the priority in Task Manager, you set it within Prime95 itself, using the process I described.

Hoot

 

[Ralf Hutter]

Seeing 50% utilization when you're running one program on an HT-enabled processor is normal. It _does_not_ mean you're only using 50% of the power of the cpu. It's just poor design in Windows' task manager (it thinks you have two physical cpus, which of course is not the case).

Then how come I get 2-3°C higher CPU temps when I run 2 instances of Prime95 vs. just one?

 

[NookieN]

Then how come I get 2-3°C higher CPU temps when I run 2 instances of Prime95 vs. just one?

That's the magic of HT. If you run only a single-threaded task on a CPU with HT, it will run just as fast as it would on a CPU without HT. If you run two single-threaded tasks on a CPU with HT, the CPU will be doing more work overall than a CPU without HT would.

So I'm not saying that running two instances of Prime doesn't give you higher temps. I just mean that one instance of Prime on a HT chip is doing the same amount of work as it would on an equivalent non-HT chip.