Okay - I don't know where else to turn. What's my problem and how do I fix it? Short version: If I leave the side of the case on the machine, after about 3 minutes, it completely shuts down without warning. If I take the side cover off the machine, it stays on for a long time (at least several hours). Long version: I have an Asus A8SLI-Premium board, amd64x2-4400+. It WAS in a stock Antec 640 case (no added fans). I haven't had a single problem untill about 3 weeks ago. I had a problem where I couldn't boot up the machine, and using a power supply tester, narrowed it down to what I though was the mb. Sent it off for warranty work. Just got it back, and had the same problem - no boot action even when the green led on the mb lights up. i dont even know if asus did anything. SO, thinking it still might be the ps, i bought an Antec 550 Neo ps and sure enough, the computer would boot up. i installed it in the 640 case and started the machine. i also just installed a thermaltake big typhoon with artic silver 5. not 3 minutes after i turned on the computer, it shut itself off without warning. i tried monitoring the cpu temp, and it stayed very cool. all this is under idle load. So I bought an extra case fan (80mm) and installed it in the front bezel, thinking that this would work. No deal. Then I thought, well maybe the case is not compatible with this big ps, so I bought an Antec p180 case (3 120 mm fans stock, with a separate ps cooling channel) and installed the stock amd heatsink again using artic silver 5. This time it stayed on about 5 minutes before it also shut down. I tried upping the 120 mm fan speeds from low all the way to high. No dice - shutdown after 1 minute (shorter time b/c of residual heating I'm guessing). Right now, I've got the side off and it's been running about 30 minutes. I may let it run all night (running memtest86). I'm at my wits end. I've dropped more $$ than I cared to fix this problem. I don't want to run with the side off the case. I'm not overclocking. I just want this thing to be fixed. What's going on with this? Did I maybe not put enough thermal grease on the cpu before installing the heatsink? What do I do? Any help is greatly appreciated.