New build - PSU Shorting Out

I started my build last Saturday and got everything connected and in the case.

Powering on the PSU, everything lit up (fans, LED lights) and the hard drives spun up.

But there are three problems:

1. While the PSU was turned on, I hadn't actually hit the case's power on button. Everything just turned on, on it's own.

2. I got that 'oh crap' burned electronic smell. Seemed localized to the PSU.

3. Box wouldn't POST.

I did some basic troubleshooting (tested with a single RAM in one slot; tested with another PCI-E video card, etc). No change.

I brought it to a local computer shop for diagnostics (I don't have a spare motherboard, RAM, case or PSU to test with). They did some testing and said it was a bad PSU (its a Corsair 650tx). They had the motherboard, RAM, and video card out of the box and POSTing using a different PSU. Then they verified that the Corsair was bad using a PSU tester.

Right. RMA'd the PSU and got another Corsair 650tx. This time I breadboarded it outside the case myself first - just the motherboard, RAM, and Video card. POST, no problems.

Installed it back in the case, hooked everything back up, and...

Same exact thing as before. Same mysterious power on without actually powering it on. Same burnt electronic smell. Same inability to POST.

So here's my question:

What about installing a motherboard and PSU into a case would cause the PSU to burn/short out? I've already gone through two PSU's, and am nervous about trying a third.

I've checked the easy things. The mount points on the Antec 900 case all line up with the motherboard - no excess mount points to short things out. The main power supply connections are connecting properly (they only connect in one way).

Any ideas, thoughts, are greatly appreciated!
2 answers Last reply
More about build shorting
  1. Try making sure that the psu itself is turned off before you connect the power cord to it. Post back how you go because i am quite intersested to see how this turns out for you
  2. Defective power button on the case, combined with a short on the motherboard. That would be my guess.

    Did you install the standoffs correctly?
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