If your system is an emachines with ecs motherboard which has an nvidia chipset for Intel cpus, your guess is as good as mine. Have you tried contacting emachines? I don't know what cpu you have now; I would guess you would be safe with a 1066 fsb quad core, such as the q6600, which you can sometimes find used. Newer wolfdales might be a problem, since no bios update is available for this board.