Dear Combjelly:
A good test would be if Dempsey has the same problems as Woodcrest. They both fit on the same MB. If Dempsey passes and Woodcrest doesn't, it may be a problem with NGA. Then one of three things is the likely culprit, the L2 cache arbiter, the prefetchers and the FSB.
RAID controllers generally use the biggest blocks used in transfers, 4KB and up. It first goes to the cache in the RAID controller and then gets DMA'ed to the memory. Now that goes on the FSB to be cached (although device drivers should tell the CPU that that area shouldn't be cached). Now if the FSB is at fault, the massive data block (larger than even TCP/IP max blocks of 1512 bytes) might create enough noise to have some data misread every now and then. Dempsey with its 1066MHz FSB might be clean enough at the lower speed to not have the occasional data misread. Thus it doesn't have the problem.
Two, virtual memory swaps pages in and out of the RAID HDs. What if the prefetchers fetch data that will be replaced and then get acted on before the correct data gets swapped in. This kind of race condition would be hard to find. And it will only be seen when the system is under high load with not enough memory to hold all of the running programs. Per haps its the very aggresive nature of the prefetchers that gets NGA into trouble.
Three, the cache arbiter may cause core one to use what core two cached in L2. Core two may be in the process of invalidating that cache line. Granted that is a small time window, but the problem doesn't happen in either exclusive caches or independent ones.
In any case, NGA just shot itself in the foot. If this is the case, Intel just pulled a bonehead maneuver on the par of the Linux compile bug of the P3-1.13. This time they compounded it by dissing their P4s causing them to be unwanted. Oh the irony!
Pete
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