Hmm. You have case fans? The rear one is important. When you apply the thermal paste, do you get a full and even, but also thin, covering? Is the paste a cheap brand? You might need better, silver-based paste, such as Artic Silver.

[quote=paulunderwood;120146]Hmm. You have case fans? The rear one is important. When you apply the thermal paste, do you get a full and even, but also thin, covering? Is the paste a cheap brand? You might need better, silver-based paste, such as Artic Silver.[/quote]

I am using Artic Silver, do you think it worth me reseating the cooler with fresh paste?

Yes. It is important to use a thin layer to ensure good heat conduction. I assume you know how to fit a socket 775 heatsink -- its best to remove the mainboard to make sure the legs of the heatsink are put correctly through it.

Okay, I have reseated the cooler, and I'm still getting errors.

Oh dear! Is your Windows patched up from Microsoft's site?

Do you have a in-line fan speed controller for the Zalman?

With the CPU Host frequency rebooted at 150MHz, what is the temperature reading in BIOS?

Maybe you should also try setting the memory manually to its specification...

Do you have another memory stick you could try? Make sure you first reset the memory to auto/SPD before fitting it...

What is the version number of Prime95 are you using?

[QUOTE=mjbaxter;120128]

CPU voltage (from BIOS) = 1.3V
[/QUOTE]

Are you sure about this value? It is too low...
Your CPU is based upon a Prescott core, isn´t it? I think the standard voltage for these cores is around 1.5V (at least my Northwood, which is pretty similar, runs at at 1.55). Try increasing the CPU voltage to 1.5V. You may wish to improve cooling, in case the temperature rises due to this increase in voltage.

See the link to the processor specification in post #8. It is 1.225V-1.325V

Could it be a bad CPU? It works on either core alone, but not on both cores. The only reason I can come up with is some kind of fault in the cache coherency circuitry. I've never seen this behavior before.

Thank you all for your posts!

[quote=Prime95;120226]Could it be a bad CPU? It works on either core alone, but not on both cores. The only reason I can come up with is some kind of fault in the cache coherency circuitry. I've never seen this behavior before.[/quote]

I take your point, any suggestions on how I can test for this?

[quote=paulunderwood;120161]Oh dear! Is your Windows patched up from Microsoft's site?[/quote]

Yes, a fresh install with all updates, and the latest drivers for MB/video etc.

[quote=paulunderwood;120161]Do you have a in-line fan speed controller for the Zalman?[/quote]

No, it is running stright from the MB.

[quote=paulunderwood;120161]With the CPU Host frequency rebooted at 150MHz, what is the temperature reading in BIOS?[/quote]

37C

[quote=paulunderwood;120161]Maybe you should also try setting the memory manually to its specification...[/quote]

I tried this, still getting errors

[quote=paulunderwood;120161]Do you have another memory stick you could try? Make sure you first reset the memory to auto/SPD before fitting it...[/quote]

I tried this, still getting errors

[quote=paulunderwood;120161]What is the version number of Prime95 are you using?[/quote]

The latest version (2414)


This is a very frustrating problem!

Have you tried running the memory at 333MHz i.e "x 1.66" of 200MHz ?