Could this be anything other than a faulty PSU - and how to prove it
 

Jetway MA3-79GDG combo motherboard
Phenom II x3 720
2x2gb DDR3
Galaxy GTX260 896mb
Tagan 500w PSU
500gb SATA
4x8cm fans
Vista 32bit
Not overclocked.

My PC is shutting down at random moments, sometimes not letting me turn back on for 5/10 mins, sometimes letting me turn on straight away, and sometimes erasing the CMOS.

I checked the voltages with a multimeter and they seem to be OK (but this is when the PC is working, so this would not show low voltages causing the shut downs)

When it is not shutting down everything is working fine.

The wiring is fine, every connector is perfectly in place - power comes straight from the wall.

From reading my A+ book, this sounds so much like an intermitent PSU fault, and I should replace the PSU.

But, the store has already said the PSU is fine (because it worked for 5mins in their store) without sitting in their store for 5 hours waiting for a shut down, is there anyway to prove the PSU is faulty?

I will replace the PSU, but I would prefer to get a refund on the current (3 weeks old) PSU, rather than pay with my own money.

erasing the CMOS would make me think that you have a bad CMOS battery (although this won't cause the machine to crash).

Try running memtest in a loop overnight to see if it crashes or not (to verify it isn't software).

Terry
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