My K8WE (2895) with dual Opteron 280's and 8GB RAM (in the form of four 2GB\nDIMMs of Crucial PC-3200, 2 DIMMs per processor) has been running flawlessly\nfor nearly 18 months now under Windows XP-64. Just last week I fulfilled a\nneed to fill out the 4 vacant RAM slots with identical DIMMs to bring the\ntotal to 16GB. Upon booting up after the installation, everything was\nrecognized and ran just fine.\n\nFollowing the installation, I wanted to do a bit more testing to see if my\nperformance had drooped any, and so I ran the Sandra 2007 memory bandwidth\ntest. The test completed, showing a 10300MB/s performance, but triggered a\n"soft" Machine Check Exception along the way (e.g. indicating that a\ncorrectable error was encountered along the way.) I then ran 4 simultaneous\ninstances of Prime95, and continued to get several more of these Machine\nCheck Exceptions throughout 4 hours of running, but no errors indicated by\nPrime95. Then, out of the blue, I encountered a fatal Machine Check\nException that triggered an automatic reboot. Following this, I ran\nMemtest-86 for 24 straight hours without any error whatsoever, so it's\ndifficult to believe there is a problem with the RAM. Nevertheless, the\n"soft" Machine Check Exceptions continue to occur whenever I run the Sandra\n2007 memory bandwidth benchmark or Prime95.\n\nNow the interesting thing is that I subsequently discovered the following\nremedy (I'll skip over a lot of trial and error to get at the repeatable\nconsequence of my testing): Using CrystalCPUID, I change the CPU multiplier\nfrom 12x to 11.5x and the CPU voltage from 1.35v to 1.40v, and then\nimmediately change both of these values back to the default 12x and 1.35v\nrespectively. After performing this trivial exercise, which in principle\nchanges nothing, I observe absolutely rock-solid stability with any Sandra\n2007 benchmark and hours of running of 4 Prime95 instances. What gives?\nObviously, this procedure of toggling back-and-forth the multiplier and\nvoltage has some positive effect, but I don't understand it. Has anybody\nseen behavior like this?