Computer not turning on after long periods of time

HUNTER.P · 4 Sep 2013 at 22:08

Came back from a trip away a week or so ago and one of the first things when I got back was to turn the PC on. But had no luck - pressed the power button and nothing... checked the PSU was on and tried the on switch on the motherboard as well.

With no luck with this - I turned the PSU off and left it for a while. Came back tried again and no power up. Flicked PSU off again and had my finger hovering over MB on switch, flicked the PSU on and immediately pressed power switch. Bingo! computer booted up.

This is how I've had to start my PC for the last few days now and am completely stumped as to why its happening? Even after a day out it wont turn back on, but if I turn it off now and press the on switch it will power up without a hitch :confused:

Any ideas?

wazza300 · 4 Sep 2013 at 22:13

Faulty front panel power switch? Try swapping the front panel power wires with the reset power wires and start pc with front panel reset button,if it works you know the power switch is faulty

If not it could be psu issue

HUNTER.P · 4 Sep 2013 at 22:16

Forgot to mention I had tried that - but then again I have also tried the onboard on/off switch on the MB too and same issue.

How do I go about checking the PSU? Or is it a case of sending it to XFX?

wazza300 · 4 Sep 2013 at 22:21

Only sure way is to test with another psu if you can,borrow one ect

No idea where you rma for xfx,but id try their website,or rma to place of purchase

Is the crucial m4 firmware fully upto date?

hardjack79 · 5 Sep 2013 at 11:35

Not an expert in this at all, but recently had 'not booting' problems due to a faulty mobo, so in case there are some parallels...

So PSU switch turned on, wait, power button pushed.... and nothing? Do the fans twitch at all? The MB should have an over/under voltage protection that kicks in after a fraction of a second (on the order of a tenth of a second) but its long enough for some current to flow through the fans. If the fans aren't twitching at all then I'd guess the mobo is getting no power at all.

Does the PSU kick into life when you short the green mobo cable to a neighbouring black one? ie the paper clip test, Google it if you haven't done it before rather than trust my description!

It might be the PSU but it might be the mobo. Weird problem though, and good job discovering the workaround.

HUNTER.P · 5 Sep 2013 at 13:43

MB is getting power of some sorts - as ASUS logo illuminates as usual along with the onboard On, Reset, and bios LED's

No fan twitching they only start up when I get it turned on eventually.

Gonna look up paper clip test now :?

HUNTER.P · 5 Sep 2013 at 14:01

Ok clip test done - psu fan twitched and then nothing.

Plugged everything back in and ran into the same prob trying to turn PC on. But I've now found another way.

You know how you can hold those rocker switches in the middle (bit like the one in your house and you can make them spark inside?) did that accidentally and the PC booted up?

hardjack79 · 5 Sep 2013 at 14:31

Whaaat? Sounds like the PSU is producing a voltage but perhaps not the right voltage or maybe only able to supply a tiny current? Oh I dunno. It's a strange result to have it failing the paper clip test (which is about as basic as it gets) but going on to boot and run a PC (with a wacky work around). I can't think of what could have gone wrong.

From memory you need to maintain the connection between green and ground for the PSU to spin for the "paper clip test", whereas for the mobo power switch connector only a brief short is required. Did you maintain the PSU connection? If it only twitched the fan means that it must have its own cut-out and/or short circuit. I could see a situation where the initial spike in voltage through the PSU triggers an over-voltage shut off.

I assume you've completely removed the front panel switches and LEDs from the equation by disconnecting them from the mobo? Completely remove the whole lot (they may be on a convenient(TM) block) and short the two pins corresponding to the power switch with a screw driver for ~1 sec to start it up. That should at least assure you that there isn't an on-going short in one of those circuits.

I wonder if the half-way rocker switch thing just gave the PC a really rapid On-Off-On-Off-On-Off sequence and one of those transitions just happened to cause the right voltage to make it work? Like a crude PWM? Grasping at straws now.