Evening all!
I am currently experiencing a bizarre issue which I am unable to resolve... time to consult the knowledge that is Hexus!
In a nutshell...
I have a DFI Lanparty NF4 SLI-DR with 406 bios, 4 x 512Mb Mushkin PC4400 Black, and naked Opteron 144 CABNE. PSU is an OCZ Modstream 520, GPU 7900GTX, 1 Spinpoint HDD, 1 Pioneer DVD-RW, OS XP32 SP2.
The rig is under high end water, with load temps @ 2.9Ghz/1.65v of 30 Centigrade. The chip will sit at load all day long crunching with prime, no problem. This is with the memory @ a max of about 235Mhz.
Now, here comes the issue... with the CPU @ default, the memory will crunch prime all day long @ 285Mhz. I have also run memtest for 12 hours @ 285Mhz, CPU @ default with no problems... However, try to run them together, mem @ 285, cpu @ 2.9 and instability ensues. CPU @ 2.8, mem @ 280 is still unstable and the memory only becomes stable at around 235 with the CPU overclocked. What is baffling is that individually they're happy to run at these speeds.
I do run the memory on a divider as the FSB is normally run anywhere between 300 - 400 in the search for stability. Low FSB's are not really optional as the max multi of the CPU is 9, though I have succesfully run memtest @ a straight 285 FSB with a 6 - 7 multi and stock volts on the CPU to verify the issue is not FSB/Divider related.
Memory timings are a lenient 8-4-4-2.5. The board will happily run the CPU @ anything up to 475 FSB, so I have tried all FSB/Multi combinations below that to try to stabilise the memory but to no avail.
My initial thoughts are the memory controller on the chip causing the problems, and therefore an unresolvable issue, but your thoughts on this would be greatly appreciated. Many times in the past I have overlooked the obvious and I am hoping this is another classic example...
Regards, K22