Strange power problems with Asus P5QL/EPU

[ribbit2]

I have a very strange problem with a PC Specialist-built desktop machine, which has been running beautifully since Dec 2009. The machine had not been used for a few months and would not power on properly. The symptoms are as follows:

Turn on the power and the red light on the built-in card reader comes on (along with the green light on the motherboard). Press the power button the front of the case and nothing happens. Then slowly the fans will begin to kick round, first a little nudge, gradually building to a short spin. The DVD drive will make its usual disk detection noises. This goes on for a while and eventually the blue light on the power button will come on briefly, then for longer and longer periods. Eventually the BIOS screen will appear, then it will power off and start again. This keeps going until it gets as far as the Windows boot, then typically it will power off half way through and start again. After a long time it eventually gets the point where Windows will start, after skipping through the Windows failed to start normally screen.

I have replaced the button battery for the CMOS, but that has made no difference. My initial thought is that there is rechargeable battery somewhere which is not holding charge - this is further confirmed by leaving the machine plugged in for half an hour before attempting to start it - it will then start up first time as normal. If you only leave it for 5 minutes it gives up halfway through starting Windows. I am unable to find a rechargeable battery anywhere on the motherboard (or indeed anywhere inside the case) and I can find no mention of one in the motherboard manual, or after repeated Googling of the motherboard.

In 30 years of computers I have never encountered such a strange power issue.

Does anyone have any idea what it might be?

Many thanks,

Robert

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Asus P5QL/EPU | Intel Core™2 Duo E8500 (3.16GHz) | 4GB Corsair XMS2 Dual-DDR2 800MHz | 500GB SATA Hard disk | DVD writer | 512MB nVidea GeForce 8400GS | Internal 52-in-1 Card Reader | Silver/Black Trident Case + 2 Front USB | 350W Dual Rail PSU | Windows 7 Home Premium 32 Bit

 

[paul1224]

You may well have done this anyway but always begin with the simplest!

Have you unplugged the plug, switched off the power at the back of the PC (the little button), taken out the power cable from the back of the PC, left it all for a couple of minutes then plugged it all back in? Chances are it won't resolve the issues but a full discharge of power and reconnecting everything to make sure it is all secure is worth a try.

Other than that I am not aware of any other rechargeable battery other than the CMOS, I guess it could be a power issue with the PSU due to how long you have had the PC (I have a very similar PC spec to you) and due to the period of non-use. If you have a PSU Tester that would give a good indication whether it is becoming faulty.

 

[ribbit2]

Thanks for that, Paul. The machine is normally left with the extension it is on physically unplugged, and whilst I was mucking around with it with the case open, I had everything disconnected (all peripherals, including keyboard, mouse and screen). I was also using the power switch on the rear of the machine to get it out of trying to start up - holding the front power button down for 10 sec doesn't work unless the machine has started successfully. I also checked that all the fans were free to turn.

I guess it could easily be the PSU and it would be easy enough for me to swap, but I don't have a spare to test with, nor do I have a PSU tester. It just seems an odd fault, as once it has sat for half an hour it runs up absolutely fine. It evidently delivers some power as the green LED on the motherboard lights as soon as you give it power, which is probably +5V, but it may be that the other outputs have a fault. I'm afraid that PSUs aren't my thing - I'm more the software side. Any ideas on how to test it? I should probably add that the machine is my Dad's and I'm not sat in front of it, but I can go armed with stuff next time I visit. If we can narrow it down to being 90% probability of being the PSU, I'd just buy another and fit it on my next visit.

Thanks R.

 

[paul1224]

I have a basic PSU tester like this which does the job.

I can only really surmise that it would be a fault with the PSU in some way, it is strange that after a while it powers on ok but that could be a sign that it is faulty and after a certain amount of time with the power on it seems to work. When the PC is on does it work fine for a prolonged period of time? Also have you tried leaving the PSU plugged in (via the plug) and the power button on the back of the tower on but the actual PC off and then powering the PC on, does that boot it first time? Just trying to work out why it almost seems to need a power build up before booting correctly.

 

[ribbit2]

Thanks again, Paul. I didn't realise that a PSU tester would cost so little - I have a half-decent multimeter and was expecting it to be in the price range of that. Might be a handy little box of tricks to have knocking around the place.

What you describe is exactly what we have been doing. Leave everything plugged in, with the PSU power switch on, but hold off pressing the power button on the front of the case for about 30 mins before trying to use it. It works absolutely fine after that for hours at a time. Not tried it again immediately after shutting down, or after unplugging for a few minutes, but certainly the next day you have to leave it on for the half hour again before you want it. It's almost like it's powered by valves! :wacko:

Thanks R.

 

[paul1224]

Yeah it is strange, maybe someone with more knowledge than me will post some insight as the only other thing I could suggest other than testing the PSU would be to also try the PC plugged into a different wall socket just in case it is that socket that has some form of fault, unlikely but may be worth just trying.

Other thing I would do if you feel comfortable is to open the case up and make sure all connections from PSU to MOBO are definitely secure, possibly unseat and re-seat the connection to MOBO just in case it has come very slightly loose and the power source isn't getting through as securely as it can.

Hope it gets sorted, apologies I couldn't really offer any better insight.

 

[ribbit2]

I had a good jiggle whilst I was I had the lid off and found nothing obvious. Next visit, I will be a bit more systematic about it, particularly as I'll have to unplug everything to use the PSU tester. The wall socket also powers a cordless phone base-station, which has had no issues, so I have no reason to suspect the socket. A loose connection internally is more plausible, as the machine was moved in the last year, though it was working without issue for a few months after that, before a period of non-use.

Many thanks for your suggestions, Paul.

If anyone has experienced a similar issue to mine, then I'd really love to hear from you.

Thanks R.

 

[ribbit2]

Bump. Still looking for ideas on this one. Would really like to hear from anyone who has experienced something similar.

Thanks R.