PC won't boot up.

[Deleted]

Hey, I'm having problems with starting up my brother's PC. Story:
My brother's Monitor broke like 2 months ago so we haven't used since. Only thing I did then, is I checked whether it sure was the monitor - connected to my monitor - all worked, great! put it aside and never touched it since. So we finally got to buying new monitor and connect everything and boom! PC just doesn't want too boot up. Starts for 1` sec and turns off and so it goes like that. I thought surely it was PSU dying, seems not, changed the old one for a new OCZ 500w PSU, now PC boots for 1 sec, turns off, then boots and just stays like it is, no signal to the monitor, just fans blowing.
Now I'm out of ideas here, I've looked for bulging capacitors - none, all plugs connected. Can't check atm if it is GPU, because Mobo is pretty old so there's not VGA or DVI outputs on it >< Any ideas? Thanks.

Specs:
500w ocz psu
Old Gigabyte LGA775 mobo
intel core-2 duo(can't get exact number)
GeForce 7800GT

[ati87]

My first guess is motherboard because (personal experience)

if it was the graphics card the computer would still boot except except the screen will look broken
if it was the power-supply the computer wouldn't even boot, their would be no power
However if the motherboard breaks down the computer won't boot but stuff like fans will

Not sure what happens if the CPU is breaks since I never had that happen to me

[Cyanotical]

Not sure what happens if the CPU is breaks since I never had that happen to me

the fans turn on, but the board doesn't POST

[Lemmiwink]

Starts for one second then nothing? Is your cpu fan properly connected? your 4-8 pin CPU cable connected? Is the CPU overclocked? sometimes it helps to take out the cmos battery on your motherboard for about an hour, then plug it back in again and voila everything works

[Deleted]

Yeah it starts for a second and then turns off, then starts and stands still. Everything's properly connected nothing's overclocked.

@Cyanotical - So it's likely the CPU? I have another core2duo laying around that works so I will test it tomorrow.

[Themos]

The proper thing to do is to disconnect all non-vital components and insure you can post. Then reconnect them one by one until you find the issue. Complete specs might help a lot, 500W seems low for tower. You might simply not be supplying enough Wattage to your system. Take out the video card, disconnect all the drives, and any other slotted cards you have and see if it posts (CPU clock and memory counter).

It might be something as simply as the CPU fan, but you won't know until you do a naked boot/post test.


edit -- I looked up 7800GT wattage, and it says minimum 450W. My best guess is not enough power. You likely need a 650W+ supply.

[Deleted]

Well, it has been working for 1,5 years with a 400w PSU without a problem, but will look into it.

[Lemmiwink]

Did u remove the cmos battery?

[Deleted]

So, I removed and placed back the CMOS battery and removed GPU card for now. Now it boots up for 3 seconds and does a beep sequence I can't really describe.(something like 1 long-1short-1medium long(taaaaa-ta-daa)) Is there any guide to identify what that beep means?

EDIT: Found this video right here , and mine sounds like RAM problem. I have 3 sticks or RAM each 1GB and 2 are the same brand and 1 is other so this might be the problem. Will report back after more testing.
EDIT: Indeed it was a defective RAM stick, PC now POSTs and boots. Thanks for all the help. /closethread