Hey so I have been having a problem with my tower over the last month and have exhausted myself trying to troubleshoot/fix it, and am totally open to suggestions. The Machine: Acer brand main board (EM61SM) amd athlon 64 x2 dualcore 5000+ (2.6 ghz) 4 gigs ddr2 ram (been in it for a year) Radeon HD 5670 1gig ddr5 gpu w/ passive cooling 1 500 gig 7200 rpm WD hdd 1 300 gig 5200 rpm seagate (not in the machine anymore) Ok so it just hard crashed on me one day, no bsod, no error messages, nothing in the event log about it at all, except to say that windows didn't shut down right last time. I can play games fine, but if I start multitasking on the desktop or playing flash games in firefox or using to many tabs in firefox it crashes. I completely dismantled the machine, cleaned it, cleaned the circuits on the ram and GPU (white eraser) cleaned off old thermal paste and the CPU cooler, applied new thermal paste, put the whole thing back together and it kept doing it. made me think it was a PSU problem. so I put up with it for a few days until I could get a new PSU, and in the mean time I ran memtest 86 on it for 14 hours straight (13 passes, no errors) I ran furmark and prime 95, both for 6 hours each with no issues, monitoring the temp's (never reached over 60 degrees) all the voltages seem to be steady and where they should be (open hardware monitor) and I bought a new PSU yesterday (EVGA 500B 500 watt PSU) and popped it in the machine, got it running and started multitasking to check, hard crash. so I backed up my data and wiped the drives, fresh install of vista, and I barely got the thing going again as it crashed just as I was logging into vista for the first time, at the part where it says "testing your system components please wait." so I can play games on it fine (decent games to such as metro last light, dayz, payday 2, etc...) but as soon as I try to multitask or open too many tabs in firefox it crashes. any thoughts on the matter?