I just upgraded from a pair of Corsair CMX512-4000PRO (TWINX1024-4000PRO) memory modules to a pair of Corsair CMX1024-3500LLPRO (TWINX2048-3500LLPRO) memory modules, and I'm seeing some odd problems. Basically, if I run both modules, the system crashes. I can use it for some unpredictable amount of time, and it crashes. The only way to predictably crash it is to play Elder Scrolls IV: Oblivion for 10 minutes (as it's about the most demanding game in existence right now). Rarely do the first 5 minutes pass without a system crash. However, if I remove EITHER module, things run much more smoothly. I've run the two 512MB modules in this same system since I put it together in January (that memory was a holdover from my previous system), so I know the motherboard's DIMM bank 2 is not bad. In fairness, I haven't run either module individually for long enough to verify for certain that it's as stable as my previous memory modules, but I've run Oblivion for much longer than 10 minutes with each of them. Detailed system specs are in my profile, but in a nutshell: DFI LanPartyUT nF4 SLI-DR Expert motherboard Athlon 64 X2 4800+ CPU 2GB Corsair TwinX Low-Latency memory eVGA GeForce 7800 GT video card SoundBlaster X-Fi Platinum sound card Nothing is overclocked in this system (the plan was to get everything running perfectly stably before I started bumping the speed up a bit), and everything is running the latest drivers (I just updated the MoBo BIOS yesterday just in case that improved memory compatibility). I've attached three Minidump files from crashes that generated BSODs (all of which were a bit different. I had STOP values of 0x00000050, 0x0000007E, and 0x0000008E). Unfortunately, most of the crashes are hard freezes. The whole system completely freezes, and there's nothing I can do to recover it. When this happens in Oblivion, the sound keeps looping, and upon reboot, the MS problem report tool tells me that the nVidia display driver is what crashed. When it happens elsewhere in Windows, the problem report tool generally doesn't come up upon reboot to give me an indication. I've run MemTest86+ (conveniently included in the MoBo BIOS) without any problems. I ran one module for 7 passes, the other module overnight for 22 passes, and then both modules together overnight for 13 passes. No errors in any of the tests, and no crashes or lockups during any of the tests. I'm hesitant to try to get Corsair or ZipZoomFly (still have a few days before their return policy expires) to replace the memory because I can't seem to find any evidence that it's faulty, but I don't know what else could be wrong. This motherboard is certainly common enough, and Corsair XMS memory is certainly common enough that I'd have expected to find any compatibility issues between the two when researching this purchase. Any help would most certainly be appreciated!