I have an ASUS P5K/EPU LGA775 motherboard and a Core 2 Quad Q9550 CPU - 2.83GHz running on Windows 7 Ultimate 64-bit. My motherboard says that it is compatible with the quad core but it fails to read all 4, it states that I have only 2 CPUs. When I boot my computer I get a message saying "Unknown CPU detected, please update your BIOS in order to release its full power! Press F1 to continue." I have tried updating the BIOS through the ASUS auto updater and I currently have version 0501. When I run msinfo32.exe it reads the CPU as being correct but when I go to enable and disable the cores in msconfig>boot>advanced options I only am able to choose 1 or 2. Would a reformat be inorder or is my motherboard not able to handle this specific quad core?