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I've come home today and switched on the PC I've built a few months ago only for the machine to whir for a few short seconds and then die. It repeats this until I disconnect the power lead. Nothing is output to the screen and this cut out happens very quickly after switching it on.

What could this be and how could it be fixed? Is it the power supply? I'm in despair :-( My spec is below, everything is new and was bought and assembled within the last 6months, system has been fantastic until now.

Power Supply: 620W CoolerMaster Real Power M620
Motherboard: Gigabyte GA-X58A-UD3R Intel X58 (Socket 1366) DDR3
Processor: Intel Core i7 930 2.80GHz @ 4.00GHz
OS Windows 7 64bit

Sapphire HD 5770 Vapor-X 1GB Graphics card

1TB Hitachi HDD 720GB Seagate Barracuda HDD 350GB Seagate Barracuda HDD EMu 0404 PCI Soundcard

D-Link PCI-E wireless card Samsung DVD RW drive

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It might be helpful to add expansion cards and hard drives to this as well. – Shinrai Nov 18 '10 at 19:54
just added as requested – benwebdev Jan 3 '11 at 12:20

Exactly the same thing happened with my HTPC, when I tried adding a second hard drive. It worked fine with another PSU, so I RMA'd the faulty one back to Seasonic.

The machine could actually start with the faulty PSU with one drive, and I could connect the second drive after POST.

Try taking off any peripherals that you can, which use the 5V rail and see if it starts.

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My first guess would be the power supply as it sounds like it tries to start and then fails. I assume you have no other good parts to test against?

Try disconnecting all extra add-ons, hard drives, optical drives, and remove any expansion cards. From there, you can limit the problem down to the motherboard (cpu, ram) or the power supply as the issue. If it starts working after removing all the extras, start adding them one by one until you pinpoint the offending component. It could be the motherboard, but the conditions you describe do suggest the power supply as it wont even hardly power on. A failing or overheating CPU would cause a machine to turn on for a few and then shut off too. My order of concern would be power supply-->motherboard--CPU. When you have it a part, make sure to examine the motherboard for any burn marks or discoloration. Also, take note of any smells. Stick your head near the motherboard and see if you notice anything. The power supply would likely give off a burning smell too, so check that out.

If you bought parts new, the power supply should be under warranty and you should be able to get a replacement.

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ok, I've disconnected all HDDs, graphics card, sound card, CD drive and still the same problem. – benwebdev Nov 18 '10 at 20:16
looking at the motherboard manual now just in case. – benwebdev Nov 18 '10 at 20:17
@benwebdev Do the cpu cooling fan and any case fans turn on at all? or is it just the power supply fan you hear turning on? – Troggy Nov 18 '10 at 20:19
@Troggy - yes the CPU fan and all three case fans switch on - until the supply cuts out after about 2-3 seconds – benwebdev Nov 18 '10 at 20:23
@benwebdev Smell anything weird or burning smell? see anything? Is the power supply getting hot? Got access to known good power supply to test with? – Troggy Nov 18 '10 at 20:29

I definitely vote for dead psu

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