Just built a machine this evening. All plugged in correctly. Went to start it up. Pressed power and it sort of choked. Seeem to boot, then turn off almost, then boot again fine. However after 15 seconds it just turns off. I get one bleep from the Bios on start as per normal. But every time it just turns off after 15 seconds or so. I was a little concerned the heatsink was not on properly. Would this account for it possibly? Any way of knowing whether it's on properly? Any suggestions are urgently needed please!
C2D 6300+ w/ stock HSF
2x1GB Geil 6400 DDR2
HIS X1950 Pro 256
Seagate 320GB SATA II
Old IDE DVDRW drive
Possibly could be it if you didn't fasten the HSF enough... though with the push pin system, it's rather hard to screw up there. Your speaker should give you a long warning beep until it automatically shut offs if your CPU was overheating. Make sure your speaker is connected properly first to be certain. One beep depending on the length and number (edited) from the bios could mean a lot of things but from what you have said, I get the feeling it sounds like your computer POSTs which means you should be able to see the start up screen and get into your bios. Is this the case? Does nothing show up on your monitor? Did you try reseating your electronic components like your RAM and Video card? I'm taking it you really did plug everything in.
Your ram requires i think 2.1 v to run check to make sure. Your motherboard supplies i believe a default voltage of 1.8v. Try installing one stick of ram then see if it boots go into the bios and change it to the manufacturers specs for the ram and then see if it will work.
The only way that could be causing it is if the polarity was wrong and your mobo shuts down to be safe. But are you running a raid (even with only one in raid 0)? The wrong raid settings or drivers have been known to shutdown many of my pc's.
No raid. Now ive just remounted the hsf and noticed when i took it off, 2 of the pin things popped out without twisting the plastic caps on top of them. Maybe ive found my answer? I'll remount now. Its a pain in the arse not knowing when it is or isnt on properly.