Rapid power cycling

[rabbatiello]

Hello, I just built a very powerful computer with a Core i7-990X, an EVGA motherboard with an Antec 1200W power supply. The system was functioning fine for a few days, but after a restart the computer will not turn on. At first, it froze at the POST screen, but now it turns on and power cycles every three to five seconds. We have also noticed that one fan, connected directly to the power supply with a Molex connection does not spin when the computer boots.

 

[Outlander_04]

http://www.tomshardware.com/forum/288241-31-faqs-build-advice-buyer-guides-troubleshooting

 

[Twoboxer]

Nowhere near enough info to hazard a guess, which in part is why you got the "checklist" repsonse.

It failed after a "restart". What kind of restart? What if anything caused you to restart?

Assuming you did nothing to disconnect any of the mobo connections, the first thing I'd suggest is to clear CMOS, and try to get into BIOS to reverse any auto-OCing settings and load (optimized) defaults.

If that doesn't get you further, remove all but one vid card (dunno if you have more than one) and all but one stick of memory (dunno what you have) and try again to get into BIOS.

If that doesn't get you any further, try substituting a known working psu, even if it is (in your mind) too small for the load.

Let us know what happens.

 

[need4speeds]

Something is not wired right or is shorting out. Careful sometimes molex connectors can be put on backwards. They do have small 45 degree spots to try and prevent this. But some connectors can flex and still plug in backwards.

-Sometimes cheap fans from china come shorted or are wired wrong.

-The case's usb wiring/plugs are shorted out? The wires going to the lcd lights for the power/hdd light are wrong or shorted out. Try just running with the on-off switch wire only first to test.

The p/s is tripping and resetting on overcurrent or overvoltage protection.

-Make sure the board is not shorted anywhere on the case. Sometimes it can flex and touch the metal. Use something soft like ear plugs or roll some electrical tape in a ball. Reinstall with some spots with this making sure the board sits nice and doesn't touch. Often you need this below the pcie slots because the heavy cards flex the board a bit. It's not good for the board for it to sag or bend.

-A usb device could have failed or be shorted. A dead hdd will short the p/s too.

1. Check the board. reinstall.
2. This is the "KISS" method: Run the system with one mem stick and least amount of parts possible to get a post screen.
3. Plug in stuff one by one. restart and see if it still posts ok after each item is installed. Maybe put the video cards in first. Then the fans one by one. Plug in the drives and get windows working again last.