I started building a new system last night, and had it working for probably 30 minutes or so, and was working through the BIOS to setup RAID. During one of the resets, however, the PC wouldn't start up again. More specifically, what I did during that reset was add a power cable to each SATA drive, rather than having them hooked up on the same power cable.

After the startup, pushing the power button the case did nothing. No fans started up, no LEDs lit up. Nothing. I stripped everything, minus the motherboard, PSU, and RAM, just to be sure nothing was interefering with anything else. Also double-checked that all the case wires were plugged in correctly. Still nothing. This was all last night.

This morning, I was jiggling some cables to try to get something, when I noticed that if I pulled the main 20-pin power cable out of its seat just a little bit, the PSU fan would start up, and the case's power LED would light up. The CPU fan didn't start, though. And if I plug in a case fan, that will start up, as well. But as soon as I fully seat that 20-pin again, everything shuts off.

So I figure it's a problem with one of three things: the PSU, the motherboard, or possibly the case power button. Does this behavior sound familiar to anyone?

Here's the products in question:

Mobo: http://www.newegg.com/Product/Produ...
PSU: http://www.newegg.com/Product/Produ...
Case: http://www.newegg.com/Product/Produ...

I didn't know that Corsair was in the PSU business. The specs look good though.

"But as soon as I fully seat that 20-pin again, everything shuts off"

You twice referred to the main plug as 20-pin. It should be 24-pin (or 20+4). There should also be a square 4-pin ATX12V plug connected to the board to supply power to the CPU. Are you sure your wiring is correct?

Yes, sorry, the 24-pin. As I said, it was working for a good half hour or more, as I was configuring the BIOS for RAID.

I went home at lunch to play with it some more, and it definitely seems to be the motherboard. Depending on how I jiggled the DC power 24-pin cord in the seat, I could get different fans and LEDs to turn on: in one position I could get PSU fan, CPU fan, and chassis fan to turn on; in another I could get the PSU fan and the power LED to turn on; etc.

Then I brought in the PSU to work after lunch and tried it out on a new Dell 745, and it booted up fine, without any quirks. Couldn't find all the drives, of course, since only the main power was plugged in, but everything was fine power wise.

So looks like I'll be talking to NewEgg to get a return. Dangit.

Do you have a different PSU that you can try with the new board?

If I understand you corrrectly, you are connecting and disconnecting while under power. That is a no no.

I wasn't messing with the power before the problem cropped up. Once I completely lost power - and at the point thought it to be a PSU problem - I noticed the phenomenon when unplugging the board.

Ultimately, I suppose I don't mind getting a new board, since I wasn't thrilled with the Gigabyte anyways. Probably be ordering an Asus or eVGA to replace it. Just a pain to have to play the return game, especially since I was so excited for the new system only to reach this anticlimax...