ok people. here is one for yea that i tryed last night but not too sure on. i have a few ideas but just a few. heres the problem i just built a new computer into a case that was on order for a month. specs: aspire Qpack case amd 3400 S754 CPU 1gb samsung memory asus K8v-mx motherboard aspire 420W PSU 2x seagate 160gb hdd's samsung DVD burner. quadro 750xgl 256 card. there are no lights in the case. and there is a 120mm fan at the rear. the CPU does not get hot. it sits about 39 and case is about 30. max i have see the sys go to was 51 it will happen in windows when doing nothing. or it will happen when chatting on net or anything. its totaly randome. does anyone have any ideas? i have tested mem with memtest 86. the cpu in anouther system for 4 hours works fine. video was pulled from working PC. and its not getting hot. and i can get 3dmark 2005 to run just fine on it too but the second time i did it, it restarted after i finished it. also the system is on a UPC that is also running anouther pc and its fine. and the power status is also fine. i aws thinking possably the PSU or a bad hdd, anyone else got any ideas tho that i should try?