PC "throbs" on shutdown - now won't power up - HELP!

[LenSessions]

Over the years I’ve found answers to many problems on Tom’s Hardware but I’ve never needed to post my own question before. Either I’m searching for the wrong keywords or this is something new & weird.

I have a Medion Akoya P4314 and, for the last few weeks, as soon as it shuts down at night it briefly powers up for a second. Then again. Then again. It varies between 6-18 “throbs” before it stops. This was obviously a symptom of something but what? It wasn’t causing a problem so I stuck it on the back burner. I’m sure you can guess there is not a happy ending. Last night had the usual “throbbing” on shutdown but today pressing the power button just causes an endless cycle of “throbbing” but the PC never stays on. There has never been a startup problem before.

Knowing almost nothing about hardware I’d suspect the PSU but I thought I’d better ask an expert in case it’s really something more obscure, like a motherboard issue. Please let it be some simple component I can just swap out!

I don’t know what further information you may need to ID the problem but whatever it is I hope I can supply it. I’m in your hands.

 

[Ubrales]

Check the easy things first. Start with the 8-pins (4-pins) CPU power connector. Make sure that it is plugged in securely and the latch engaged.

 

[LenSessions]

I wouldn't even have known where to start with a diagnosis! Unfortunately I can report that the CPU power connector is firmly attached so it isn't that.

 

[Ubrales]

Here is a good guide for trouble-shooting: http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems

 

[LenSessions]

Wow. That's an impressive list. It's handy for people building their own systems as well as people like me who rarely take a peek inside except for dusting! It may take a while before I report back...

Here is a good guide for trouble-shooting: http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems

 

[Ubrales]

Wow. That's an impressive list. It's handy for people building their own systems as well as people like me who rarely take a peek inside except for dusting! It may take a while before I report back...

Take your time and follow the guide step by step. You will get to the solution.

 

[LenSessions]

Got as far as step 6 but it seems I no longer get any power at all when I try to turn on now. I guess that means it’s time to replace the PSU – if I can work out how they got it in there in the first place (some room to manoeuvre would be nice). To be continued.

 

[Ubrales]

I tried to get some specs on your computer and did not get much info on the PSU. Can you peek inside (with the power OFF and computer unplugged) and let me know the make, model, and the size?

 

[LenSessions]

I was going to say ‘no’, because I still can’t work out how to get it out of the case. BUT I can see a part number & with a little googling I’ve discovered that it’s apparently made by FSP Group specifically for Medion with model no. FSP400-60EMDN (400W). Used ones turn up on ebay occasionally but as this is an OEM component I suspect I’ll probably have to buy someone else’s equivalent if I want it new & now. Trying to work out what that will be is a job for tomorrow. I’m going to rethink how to extract this PSU first - and test it to make sure that’s really the problem.

 

[Ubrales]

http://www.corsair.com/en/blog/testing-your-corsair-power-supply

There are other tests for other PSU's at Corsair's site and also at other sites.

 

[LenSessions]

Hardware’s REALLY not my thing. So forgive me for feeling very satisfied with myself for having just extracted and tested a PSU. Had to remove the fan to get it out so I’ll be getting acquainted with thermal paste in the near future. Took lots of notes & photos of where all the PSU cables went, too. (All connections were tight so that wasn’t the problem.) And surprisingly, the PSU worked!

So I should try the power button next? I’ve traced the wires to the MOBO. I’ll reattach the fan & reconnect the PSU wires then I’ll bridge the 2 MOBO prongs and pray when I switch on the mains - cause if that doesn’t work I suppose I'll have to get a POST card to test the MOBO? I almost sound like I know what I’m talking about.

 

[Ubrales]

Hardware’s REALLY not my thing. So forgive me for feeling very satisfied with myself for having just extracted and tested a PSU. Had to remove the fan to get it out so I’ll be getting acquainted with thermal paste in the near future. Took lots of notes & photos of where all the PSU cables went, too. (All connections were tight so that wasn’t the problem.) And surprisingly, the PSU worked!

So I should try the power button next? I’ve traced the wires to the MOBO. I’ll reattach the fan & reconnect the PSU wires then I’ll bridge the 2 MOBO prongs and pray when I switch on the mains - cause if that doesn’t work I suppose I'll have to get a POST card to test the MOBO? I almost sound like I know what I’m talking about.

I am very impressed at the organized manner in which you are going about problem solving!

When I work on my car or on other appliances at home, I do take some digital pics to help me when I re-assemble the parts.

Yes bridging the two "Power ON" header pins on the mobo would be the right way to eliminate the start switch as the problem.

And yes, you do know what you are talking about! Keep going!

 

[Ubrales]

Something tells me that the RAM may be defective - check one module at a time (make sure it is plugged into the correct RAM slot per motherboard manufacturer's guidelines.

You can also use "Windows memory checker" and/or "memtest86"

 

[TenPc]

If you've been using the 400 watt PSu for such a long time, it could be that not only has the motherboard carked it but also one or all of the ramhave been shorted particulaly if you have been playing PC games for a long period of time.

Sometimes it only takes a heavy session or two (or an attachment of a usb device like a printer of iphone etc) to over-extend the power requirement that does cause the non-operation of the PC.

I'd suggest you replace with at least a 600 watt PSU.

 

[C12Friedman]

I'd suggest you replace with at least a 600 watt PSU.

600W? I don't understand the reasoning of the recommendation

 

[LenSessions]

I’ll be honest – I reconnected all the PSU connections but as I have no thermal paste in the house I just seated the fan back in position without it. For a few seconds that shouldn’t be a problem, I hope. Tested power switch – success. Powered up just fine. Turned off. Reconnected the power switch & tried turning it on that way. Nothing. Disconnected the power switch & tested with screwdriver again - powered up fine. It looks like I may have a faulty power switch, whodathunk!

Looks like I’ll have to remove the hard drive to get to the switch mechanism. I am completely clueless about fiddly components like this – I don’t know if they’re all fairly standard or if I’ll have to end up rigging some oddity dangling outside the case. I’ve got nowhere decent in my area to pick up arctic paste so I’ve ordered some online (& a hard drive caddy ‘cause I’m really missing my hard drive – working from back-ups really isn’t the same). When I’ve got the hard drive in the caddy & out of the way of the switch, and the fan properly back in place I expect I’ll have the next instalment in a few days. Just wondering if I should get a POST card just in case..?

 

[LenSessions]

OK – everything’s back in the case & securely connected, except the ATX power switch (which I tried again & didn’t work). Shorting the ATX switch connectors manually gave me power…
I reached the screen that gave the option to run Windows startup repair, which I did. This seemed unable to diagnose the problem but did offer these details:

Problem signature1 6.1.7600.16385
Problem signature2 6.1.7600.16385
Problem signature3 unknown
Problem signature4 21348520
Problem signature5 AutoFailover
Problem signature6 1
Problem signature7 No root cause

I also ran a Windows memory diagnostic which was OK.
Throughout I had a decent breeze from PSU fan & CPU fan.
Then the system stopped powering on at all(!), although I got a second or two of fan movement whenever I turned on OR off from the back..?
Now that has stopped happening too.
Hope there are some clues!

 

[Ubrales]

Replace the switch, and instead of a Windows repair do a complete re-install of Windows. This way you are starting out with a known good OS.

 

[C12Friedman]

^ +1
To replace or repair the switch, you'll need to remove the front panel completely. The standard front panels are either pull up from the bottom to remove or sometimes they incorporate tabs just inside the side panel(s). Looking at a few case review vids should be helpful

 

[LenSessions]

Well, that's a surprise. When it wouldn't start even by shorting the connectors I thought you were going to say the problem's not the switch. Anyway, new developments…
I thought maybe I’d just give the PC time to “rest” before shorting the connectors again. It started up. For the hell of it I enabled “Reset Configuration Data” in BIOS. It booted all the way to desktop. I checked temps with speedfan (because I had no confidence in my reseating of the CPU fan) – all was well. I checked Event Viewer – either I’m too stupid to know what to look for or there’s nothing there. Then I shut down – and no throbbing back to life!

I'm ordering a switch tonight and we’ll see what happens next. The front panel is already off - managed to find all the right clips & didn't break a thing. The old switch is just dangling, connected only by the “Power LED” connectors.

 

[Ubrales]

Use "RealTemp" to check the temps - I read somewhere that Speedfan had some issues with checking temps.

http://www.techpowerup.com/realtemp/

 

[LenSessions]

This is a little difficult to describe so I hope I’m not missing anything, and I have no idea what to make of it.

Fitted new switch. Didn’t power up. Pressed it a few more times. Power came on, but pulsing (faster than the throbbing I used to get – this was a rise & fall of power rather than on&off) followed by a noisy CPU fan (that’s new), screen reported no video input.

Tried again. Constant power, fan back to a whisper, still nothing on screen.
Waited a bit between subsequent attempts…
3rd time – totally normal startup AND shutdown (no throbbing).
4th time – totally normal startup AND shutdown (no throbbing).
5th time – totally normal startup, but during shutdown it did the throbbing again – I turned off at the back after the 20th throb. The only things I did differently this time: plugged in the internet cable, ran Firefox, installed RealTemp, changed the date.
6th time – unplugged the internet cable first, constant power when I pressed the power switch but nothing on screen. Holding the power switch down shuts it off. Turning it off at the back, I get a brief burst of power i.e. mouse light flashes. Ditto when I turn it on at the back.
7th time – I’d left the power cable unplugged for a few hours before this retest. Power came on steadily, fan became noisy, nothing on screen. Turned off and retried again immediately – got power, no fan noise, nothing on screen. Turned off and retried AGAIN immediately – got power, no fan noise, nothing on screen.
8th time – couple of minutes later, pressing the switch did nothing. Turned off at the back, then on again. Pressed the switch – totally normal startup AND shutdown (no throbbing).
9th time – Pressed the switch – totally normal startup AND shutdown (no throbbing).
10th time – Pressed the switch – totally normal startup (using it now).

I can't tell what's going to happen from one attempt to the next. If there’s a pattern here I can’t see it.
Speaking with the voice of complete ignorance, could I have a capacitor-related problem?

 

[Ubrales]

Did you try out the system using a different known good PSU?

 

[LenSessions]

That I have not tried (on account of not having one). I'm tempted just to wait & see what happens next, as I just don't know what other tests to try.

Did you try out the system using a different known good PSU?

 

[LenSessions]

Replacing the switch meant I could now turn my PC on properly (thank you!) but it went back to the old problem of throbbing after shutdown, seemingly without end, so I turned it off at the back.
Without touching the ATX switch at the front, as soon as I turned it on at back it started throbbing immediately. On a whim I unplugged the network cable - and it stopped. Plugged back in, throbbed. Unplugged, stopped.
I monkied with the “Power on by PCI Devices” & “Wake on LAN” settings in the BIOS and network adapter properties in case that might stop the problem but it didn’t. The only thing that enables a clean shutdown is unplugging the network cable. Wha..?