Weird Problem with PC

[SpiderMonkey]

I was busy upgrading my daughters computer this evening with old parts from my my computer. All of the parts were working before I started (although not together). The situation is this, the computer does not start at all. If I open the case and press the power button while looking inside, I can see that CPU and case fan spin once and then stop. They don't react after that, even if I press the power button again.

There is nothing fancy in the case. 400W PSU, Wireless card, 4 x 1GB DDR2 RAM, AMD Phenom II 945, on board video card, SATA drive and DVD writer and an ASUS M4A78 PRO motherboard.

I think it might be the MB bios that needs a flash but have never seen this particular behavior before for that sort of situation. Have unplugged the RAM, hard drives and made sure the power is correctly fitted in. I supposed it could also be a loose screw under the motherboard or something like that but it's late and I don't have time to check that tonight.

Any ideas?

 

[Venomous]

Could be the PSU or mainboard.

Have you tried resetting the CMOS?
Have you got another PSU to test with?

 

[papooze]

Don't know what old parts you used but when I built a computer once it managed to start once,
but after that it didn't start because the motherboard was touching the metal case.

 

[FrancTheTank]

Check the Power connectors to the mobo, has a similar prob once, and it was that I didn't connect both plugs to the mobo. One is a 20/24pin, the other is a 4 pin, for the CPU I think. (located near the CPU- was hidden due to my HSF)

 

[KleinBoontjie]

Flash the BIOS, if that don't fix it, then it's the motherboard or CPU. Doesn't sound like a PSU problem, but check it out anyway.

You can also check all the capacitors on the motherboard to see if they are blown up(like a balloon)

 

[labratza]

had the same issue make sure the 4 pin is connected

 

[ponder]

Check PSU and related cabling.