Touching PSU reboots PC

**GiganticDays** · August 9th, 2012, 09:40 AM

Got a new build with the following spec:-

ASRock A75M-HVS mobo
AMD Athlon II X4 641 CPU
4Gb DDR3 RAM
500Gb SATA II HDD (Seagate)
Unbranded 500W PSU

System ran fine for a few days but started spontaneously rebooting for no apparent reason.
I've stripped it down and discovered the if I move the PSU slightly (the case is pretty low end and flexes quite a bit) the PC restarts.
Now I assumed that meant something was shorting out behind the motherboard, but if I run the PC with the PSU out of the case I cannot replicate the problem no matter how roughly the case or PSU is handled.

I've reinstalled the PSU and there doesn't seem to be any connection between it and the mobo (other than those that are required of course).

Any thoughts?

**stroyal** · August 9th, 2012, 10:08 AM

That is a tough one.

You sound like you are on the right track, and I'm assuming you are thorough.
As long as the stand offs are all in the right place, and in any case I have heard of, or experienced, the computer won't start, if the motherboard is shorting to the mounting plate.

If it started happening and nothing is being touched, it could be an electrical failure, in the unbranded power supply.
They are never worth the trouble.

If it is still restarting regularly, I would repeat the outside the case tests with the power supply, grounded to the motherboard.
I would ground the motherboard from one of the back panel fixtures, to the power supply, just to make sure, as that is the only difference I can see from in the case to out.

One other thing to check, is the front panel plugs being connected or not.

Substituting a different, preferably brand name power supply is the easiest way to test further.

**stroyal** · August 9th, 2012, 10:10 AM

Posted twice, but the computer I posted on is still waiting for TechIMO to respond, to the first post.

I think my last Ubuntu update went haywire, it wont print to network either.

**GiganticDays** · August 9th, 2012, 11:15 AM

Thanks.

I've swapped out the PSU with another identical one and the problem has gone.

You are quite correct re cheap PSUs not being worth the trouble. Branded from now on.