I just recently upgraded from a E6750 to a Q9550 cpu (IP35 pro motherboard, latest bios supports it) and the issue is Windows 7 is only seeing 2 cores at all times. Running CPU-Z shows 2 cores, 6MB L2 cache, etc etc. Device Manager shows 4 unknown devices under Processor selection. Booting into Vista 64-bit was initially only showing 2 cores as well but rebooting showed 4 everytime I boot into Vista 64 now. It also shows 4 Unknown Devices under the processor tab in Device manager. So my question is, what is preventing Windows 7 64-bit from seeing and using the other 2 cores where Vista 64 has no issues with it? Running CPU-Z shows what it should show, 4 cores, 2x6MB L2 cache and so forth in Vista and uses those 4 cores in task manager but not in W7-64 no matter what I try to do. Reinstall drivers, etc doesnt' seem to solve. If last resort is to reinstall W7, I will eventually but curious as to if any have run into this issue? Update: Disregard, seems checkign "detect HAL" fixed my issue. That or specifying 4 cores FROM within Vista for W7.