Just bought a refurbished PC for gaming. It's a Dell 490 vamped up with 8GB RAM, quad 2.33GHz processor, 250GB HHD and 1GB graphics. Was all working fine until I changed it so it would use all 4 cores and all of the RAM. From then the PC wanted to restart and I haven't been able to get past the start up repair, it goes in a loop and I can't do anything about it as I can't change the ram or coreusage through BIOS. I want to reset to factory as a last ditch but I can't even do that. I don't have a windows 7 disk as it was pre installed. Can someone help me please?