Overclocking to 4.0GHz

M

mut

Geek Trainee
I have overclocked my Pentium D 805 to 4.0GHz.
It runs like a dream and idles at just over 50*C on stock cooling.
However, I ran PCMark05 to check stability. During the test using internet explorer, which I think opens hundreds of pages or something (you hear it refreshing) and pushes CPU usage in both cores to 100%. After a little while of this my CPU temp gets over 60*C and then the PC crashes.
Im sure it can handle more than 60*C without simply crashing, when I first built my brother's system his CPU temp was at 78*C and he even managed to get his to 90*C somehow.

I was thinking this could be a power issue, with 100% CPU usage on both cores, im sure my power supply is getting put under considerable pressure, especially when the processor is overclocked by around 50%.
In BIOS you have the option of allowing the VCORE Voltage to be increased. I have tried increasing it slightly (up to around 1.4750V).
I didn't want to increase it any higher in case I damaged the CPU.

Anyone have any ideas?
 
It could be your RAM - what speed is that running at when you've got the CPU @ 4.0GHz? You may have to change the FSB:RAM ratio to ensure the RAM doesn't run too fast - running RAM faster than its rated speed can lead to stability issues (unless it's performance overclockers RAM)
 
I thought of that too.

I have PC2-5300 RAM. When my CPU is not overclocked it runs at PC2-4300.
I thought this was because of the low FSB speed of the Pentium D 805 - 533MHz.
When I overclock the CPU to 4.0GHz the CPU FSB is at 800MHz and the RAM performs at PC2-5300.

So I thought this would mean that the RAM wouldn't be a problem.
 
I think I'll agree to Matt555 - I have DDR400 and I had some serious stability issues. I had to put down it's frequency to 333Mhz (I have a P4 w/HT @ 3.06GHz having a FSB of 533MHz). Now it's 100% stable, only just that the machine's slower. Suggest you try to lower those MHz of the RAM.
 
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