PC Problem - Computer won't start.

[Faranim]

Here's some backstory:

My Old PC is 6 years old now, and it's been having boot problems for a while. What happens is when I try to power it on, sometimes the Motherboard (I assume it's the MOBO, can't think of anything else) shuts down after 1 second. So basically I press power, some fans spin up, and then spin down. After trying 3-4 times eventually the PC would power up and evertying was fine (no errors, strange behavior, etc). I'm guessing the MOBO has some sort of system checks it performs, and if they fail it shuts everything down.

So last night I got home from work and the clocks in my Apt. were blinking (lost power). I tried to start up the Old PC but now it just can't get going. I pulled the case open and have determined that if I un-plug the power from the Hard Drives, the PC boots up fine 100% of the time. If I plug power back into any of the hard drives, the PC doesn't start (it tries and then dies).

Can anyone think of what might be causing this? Somehow the MOBO is detecting a problem with the HDD and powering down? I'm reasonably sure the data on the drives are fine, my MOBO just doesn't want to let the PC start.

[Takedown3]

power supply is prolly toasted, i say this because when you say you plug your HDD power back in shit doesnt work

try getting a bigger psource or swapping one from another PC to see if that helps

this could also explain your boot problems over the last however many years

psource is usually the first thing i check when having problems that cant be solved by checking anything else

[Benadar]

I've had bad hard drives that would cause computers not to boot before, though I'd still get power. I'd agree that the PSU is the likely culprit here. The fact that it'd turn on and then go right off is more of a problem with the power than the motherboard (if the mobo detects something bad it'll usually give you beeps on start-up). Definitely try a new PSU, they're like 20 bucks.

[Palin]

Pretty sure your power supply is fried, get a new one, I'd reccomend 300 WATTS or higher, and it should be fixed. If not, then your mobo might be fried, but I highly doubt it.