Power loop before post, but if I reset the PSU it boots fine.

[JadonP]

As in the title, my computer just recently if I boot it up from a full shutdown starts to power cycle itself repeatedly before hitting the post/BIOS Logo screen until I hard shut it off by holding down the power button, then unplug the PSU, flio the i/o switch then plug it back in. Then it boots fine, no problems at all and runs as good as new.

This is a recent issue; I've recently done a fairly sizable system upgrade, Z97 SABERTOOTH MK1 Motherboard, Intel i7 4790k and G.SKILL Trident X memory. It's run for about two weeks perfectly fine on this setup, so I'm hesitant to call it a new hardware conflict.

I'm thinking... PSU or something motherboard related?

 

[C12Friedman]

It seems quite likely it is the PSU that's the problem here, what make and model, how old is it?

 

[JadonP]

It seems quite likely it is the PSU that's the problem here, what make and model, how old is it?

It's an Antec Earthwatts, I can't get the exact serial number at the moment but it's the 650w model. It's about three or four years old though; which is why it's on my suspect list.

 

[JadonP]

If you know how I can test that, I've got a voltmeter, I just have no idea how to tell if a PSU is starting to go bad or if it's related to the MOBO somehow.

 

[C12Friedman]

If you jump the PSU, you can measure the voltages from the pins referring to this information http://www.playtool.com/pages/psuconnectors/connectors.html the voltages should measure within ±5% of the stated voltage on the positive rails and ±10% on the negative rails
Note that that is the most rudimentary of tests and tells nothing about how the voltages are when the PSU is under a load (but it's what we got)