How to Set 8 threads in Prime95?

S

sfsilicon

Limp Gawd
Joined
Nov 1, 2005
Messages
505
I downloaded Version 25.9 of Prime95 for x86 and I'm trying to stress test my i7 930 @ 4 GHz. For some reason I can't set Prime to run 8 threads. Every time I try to enter 8 in the box which lists 4 for threads. I get an error message when I try to confirm the dialog. It says select a number between 1-4.

I double checked and have hyper threading on in the bios and I was able to set 8 threads in LinX and pass 20 runs. What am I doing wrong?

Prime95 runs fine with 4 threads and I'm seeing 100% utilization on each core.
 
Have you tried running 2 instances of Prime? It could be hard-coded, I guess.
 
It allows 8 threads on my i7-920, but that is with the x64 version.

Just downloaded and tested the 32-bit version... it allows me to use 8 threads as well.

What happens when you open up the task manager performance tab? Does it show 8 threads or only 4?
 
cyclone3d said:
What happens when you open up the task manager performance tab? Does it show 8 threads or only 4?
Click to expand...

I agree... does Windows see 4 or 8 available threads? Could it be that you don't have HyperThreading enabled in BIOS?
 
I'm seeing 4 cores in the performance tab. Not 8 threads.

I'm pretty sure I had the hyper threading enabled in the bios. I guess I could try toggling the setting and see it makes a difference.

BTW, CPU-Z is showing 4 cores and 4 Threads? Is that correct? Should it be 4 cores and 8 threads.
 
sfsilicon said:
I'm seeing 4 cores in the performance tab. Not 8 threads.

I'm pretty sure I had the hyper threading enabled in the bios. I guess I could try toggling the setting and see it makes a difference.

BTW, CPU-Z is showing 4 cores and 4 Threads? Is that correct? Should it be 4 cores and 8 threads.
Click to expand...

yeah it should be. most likely thing is that HT got disabled in the bios.

adds a good 10c to temps though :(
 
Yup, if Task Manager only shows 4 graphs under "CPU Usage History" then I'd say HT is disabled.
 
Rechecked Bios and HT was enabled. I tried disabling it and TM and CPU-Z are still showing 4 cores 4 threads.

Is there a Vista parameter that forces a specific number of cores to be recognized? I'm using the same Vista install with my previous Q6600 and I might have forced something in Vista a long while back. Can't remember anymore.

Otherwise I have no idea why only 4 threads are being displayed? Faulty CPU? Old Bios?

I'm using a MSI X58 PRO-E with Bios version V8.6. I think MSI has 4 newer ones with V8.A being the latest.
 
Figured it out. HT was enabled in the Bios. Windows Vista has a setting where you can set the number of processors. Coming from a Q6600 I had set this to 4. Follow the below if you run into the same problem.

Using msconfig, navigate to Boot > Advanced Settings and make sure Number of Processors is unchecked.

Thanks for everyones help!
 
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