What could be the problem?!!?!?

[Impruv]

Speaking for a friend:

Well I just helped him build his first computer, and the first time, it didn't turn on we found out it was a faulty PSU. So we got it replaced and it booted up!

Now, I face a problem thats never happened to me before... sometimes the computer works perfectly fine, and sometimes it just won't turn on. Different wall sockets, different power bars.. still the same problem, inconsistency!

Help? and thanks!

 

[Grantofhell]

Specs of the computer you built for the friend?

 

[Impruv]

OCZ (OCZ3P1333LVA6GK) DDR3 PC3-10666 1333 MHz Platinum XTC Triple Channel Kits 6GB \
$129.99

Intel Core i7 920 Quad-Core Socket LGA1366, 2.66Ghz, 4.8GT/s FSB, 8MB L3 Cache, 45nm (Retail Boxed) (BX80601920)
$359.99

Gigabyte GA-EX58-UD3R Socket 1366 Intel X58 + ICH10R CrossfireX Triple-Channel DDR3 2000+/1333/1066Mhz Dual GigaLAN 7.1Ch Audio 6x SATA 3x PCI-E X16
$229.99

Hitachi 1 TB

Cooler Master HAF 922 Mid Tower ATX Case (RC-922M-KKN1-GP)
$144.99

Antec 650W

Samsung SH-S222A IDE Black DVD-Writer 22xDVD+R/-R 8xDVD+RW/6xDVD-RW 12xDVD-RAM 16xDVD+R/8xDVD-R DL 48xCD-R 32xCD-RW W/Software OEM

and a ATI 4850

 

[Atomic Rooster]

"Wont turn on"? As in no power at all?

Have you checked to make sure you have no misplaced standoffs under the motherboard? Look for any shorts or misplaced wires.

 

[rohan23]

It might be a switch problem. Check your front panel connections.

 

[Grantofhell]

Does the mobo light come on at all?

 

[foothead]

It could be a lot of things. We need a very good description of exactly what it does.

 

[xXRODENTXx]

Hi, Im the owner of the computer and Impruv has helped me build it. I first thought it could be a motherboard short of some sort because when i press the power button it turns on for a split second (fans), and then stops. Possibly because the standoffs used to mount the motherboards are brass (I did not get any plastic standoffs or washers). But then I also realised that most mobos come with only brass standoffs. Ocassionally the desktop works. But as soon as I shut it down and try restarting the computer it fails to turn on again. I've managed to install the windows vista OS completely(when it HAS worked). Initially I thought it was a PSU issue, but Canadacomputers was able to replace the PSU with a brand new one. I also noticed that after around 15mins of letting the computer cool down, it boots up.
Any expert help would be nice.

Btw the new PSU was the exact same PSU as the one replaced.

 

[vampist]

Any beeps when it turns off, on?
At first I thought maybe a bios error. But if you installed Vista on it then it couldn't be the bios.

I would make sure that everything is connected and tightly secured.
Have you checked to make sure the ram is secure?

Just go through the entire computer and touch everything (connectors and such). Making sure that everything is nice and tight.

As for the standoffs I don't think it would really be that unless you can clearly see that one of them is touching a main component.
They usually have a clear circle for it to touch the motherboard and not short anything out.

Also just for sh*t's and giggles try using different connectors with the PSU.
Like switching the HDD with another wire. I just know that I had a couple of PSUs that had shorts in the wires and if you moved them just a little bit they would turn off the computer.
Try moving the wires while its starting up also. (just to rule that out)

 

[Grantofhell]

Take the board out of the case an operate it on top of a cardboard box. That'll rule out the shorting issue.