Hello, My System Specs: Pentium 4 3.2 Ghz 1 gig DDR II GigaByte GA-8I945 GMF LG DVD-RW LG CD-RW Western Digital 80GB Maxtor 160GB 500W PSU Windows XP SP2 Fans: CPU Fan Front Fan Back Fan My Problem: For the last few weeks my computer suffers from Random Lock-ups. I have made the following test: Memtest-more than 3 passes. HD Tests with the manufactor's diagnostic utilities: Data Lifeguard and Seatools. I have tested the computer with only a single Memory chip at a time(3 Mem Chips), but the lockups still happen I have made full formats on both hard drives and made a clean install of XP SP2 I have used Passmark BurnInTest, and couldn't finish the tests due to lockups. I have opened the case in order to put a real Fan(big one) outside the case. I am currently out of Ideas what can be the problem: Heat Related, PSU, CPU, Motherboard or something else.