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Strange IC7 stability problem

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HeatSync

Registered
Joined
May 16, 2003
Location
St. Louis, MO
I own one of the earlier IC7's that was released in the summer of last year. I'm having a strange stability problem when overclocking that makes me think it's the motherboard. I know there are mod's you can do to stablize this board, but I just would like to know if that is the problem I'm experiencing. I have 2x256 OCZ PC4200EL with SPD 2.5-4-4-7 timings. I have a good overclocking 2.8C (can't remember the stepping off-hand. Bought it earlier this year from exCaliburPC where they actually advertised the stepping on it). Both the CPU and MCH are watercooled with an Asetek WaterChill system. Here is a the problem I'm having:
I can overclock the CPU easily to 3.5Ghz with a 250FSB and it will pass 2xprime95 all night with both running the small FFT's. This puts 100% utilization on the hyperthreaded CPU and keeps the operation running in the L2 cache. I was even able to keep the VCore at 1.6V.
I can also pass multiple/many passes of memtest86 at 250FSB with no errors.
However, the 2xprime95 will not pass the large FFT's test which uses a lot of memory even at a VCore of 1.65V.
This one really has me stumped. I really think it's gotta be the MCH that's causing the problem here. Any insight or suggestions would really be appreciated. Thanks.
 
I'm using OCZ PC4200EL. It's spec'd at 2.5-3-3-7 at DDR533. I know the memory is not the problem; and besides, it passes the memtest86 fine. I've also tried upping the VAGP as well...no luck.
 
HeatSync said:
I'm using OCZ PC4200EL. It's spec'd at 2.5-3-3-7 at DDR533. I know the memory is not the problem; and besides, it passes the memtest86 fine. I've also tried upping the VAGP as well...no luck.

Please try what he says, first.
Reduce the RAM timings _first_ before saying what it is or isn't..computers aren't a science book...anything can go wrong or cause something else to fail.

Just because MEMTEST passes, does not mean that the RAM is stable.
Heck, the northbridge might not be completely stable but setting timings looser might help.

I've had memtest pass all day on my other P3 system, but a different tester "an old MS DOS "Memtest.exe" shows occasional errors, that memtest'86 didn't catch at all.

BTW, test#5 on memtest'86 is the most likely one to report errors.

And yes, it could ALSO be your CPU.
I've had cpus that were borderline stable, pass all day on small fft, but fail miserably on the large FFT test.
 
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