Solved PC doesn't turn on after powering off

[cedsays]

Hi

I powered down my computer and it does not turn back on. At first it would power on for maybe a second. I could hear and see the fans spin. There was also no beep the first few times. Confused, I tried again to turn it on again and the same thing happened. Now nothing turns on. The fans don't spin and no lights turn on. The only thing I've noticed was the green light on the motherboard stays on if the powerswitch to the PSU is on. I've tried unplugging everything and replugging one by one. I've tried a different PSU also. I also tried the paper clip test. I'm not sure how accurate that is but for the current PSU (750w) the fan spins for maybe 4 seconds then it stops. On the 450w the fans continue to spin (paper clip test for both) So I tried to switch out the PSU thinking it would help and no luck. Sorry if this is jumbled up and doesn't make sense to anyone.

 

[Mellon Head]

Have you checked the power switch connector to the motherboard? Maybe it has come loose.

I've never heard of the paper clip test before. Please enlighten me.

 

[cedsays]

Have you checked the power switch connector to the motherboard? Maybe it has come loose.

I've never heard of the paper clip test before. Please enlighten me.

With the PSU not connected to a power cable and switched off You take a paperclip and get it in an U shape. One side goes into green and one into black. Now plug it in and switch it on and you have a running PSU. Can you explain the power switch connector on the mobo?

 

[Mellon Head]

The power switch connector on the mobo is a header that has your power switch, HDD LED, and reset switch connectors from the front panel attached to it. It looks like this:



Wired up, it looks like this: (The red and black twisted pair is for your case speaker.)



They are pretty much all wired in the same way. In your mobo manual you'll probably see a picture that looks like this:



Have a look inside your case and try to find the header. It's usually on the front side of the board toward the front side of the case, or along the side of the board. Most of them are toward the front of the case. Make sure that the power switch connection is securely plugged in.

 

[cedsays]

Hopefully this is what you were talking about. There was no black and red but this.

 

[Mellon Head]

Looks like the right connector. johnsmith45jock reminded me that there is an easy way to test the front power switch. Unplug the power switch wires from that connector on the motherboard and short the two pins together. If the power switch is bad, the computer should start up and stay running. The power switch is momentary, so you just need to short the pins for a half second or so.

Try that and see if it works for you.

 

[cedsays]

Looks like the right connector. johnsmith45jock reminded me that there is an easy way to test the front power switch. Unplug the power switch wires from that connector on the motherboard and short the two pins together. If the power switch is bad, the computer should start up and stay running. The power switch is momentary, so you just need to short the pins for a half second or so.

Try that and see if it works for you.

I've tried it to the best of my ability and got no results.

 

[AmericanPharaoh]

Replace the Motherboard. If you're confident that your wall power, power supply, and power button are working, it's likely that there is a problem with your PC's Motherboard and should be replaced.

John

 

[cedsays]

It was only a matter of time before it kicked off. Going to be a long 4 months until I can afford it. Shall I mark as solved or leave open for a few month until I get it fixed?

 

[AmericanPharaoh]

Is this the same computer you have listed in your system specs?

Motherboard: ASUSTeK Computer INC. M4A77TD

Some of our other members may have some additional comments to add. So keep the thread open for awhile longer.

If money is an issue, maybe go with Manufacturer refurbished with 60 day warranty. Cost is about $50. for your Mobo.

 

[Layback Bear]

Replace the power input cable. May help, can't hurt. Look for any signs of being burnt.
The cable that goes from the wall socket to the power supply.
Make sure it is a cable designed for a power supply and not a video screen. They have the same ends.
My power supply cords are either 14 or 16 AWG. This is found on the cable.
The smaller cables are not rated for the proper amps.

American wire gauge - Wikipedia, the free encyclopedia

 

[ICIT2LOL]

My 2cents worth take a look at this and then test the volts at pin 8 (grey) on the 24 pin if this voltage fluctuates lower than 2.4 or higher than 6.0 volts then the PSU self test is failing and the PSU is faulty.

http://www.tomshardware.com/reviews/power-supply-specifications-atx-reference,3061-2.html

see Power_Good in section 2.

PS Use a digital multimeter not the analogue type RED lead pin 8 BLACK lead any black pin or even the board fixing screws.

It might even be worth testing the resistance between a black 24 pin lead and the board fixing screw. So set to resistance (OHMS) and touch across the machine ideally should be shut down and should read zero ohms.

 

[madcratebuilder]

Unplug all PSU cables except the 24 pin and 4 pin atx mobo cables. If it still powers on for just a few seconds it's probably a short in the mobo.

 

[cedsays]

Unplug all PSU cables except the 24 pin and 4 pin atx mobo cables. If it still powers on for just a few seconds it's probably a short in the mobo.

I've tried this. There is a green light on the mobo but nothing powers on

 

[AmericanPharaoh]

The green motherboard light means it's getting power, but doesn't mean the motherboard is working.

Pull out the RAM sticks, then try one stick at a time. See if it will start.

You can also, take the CPU to a shop and have it tested.

Perhaps, some of our others members will have more suggestions.

 

[ICIT2LOL]

Mate try leaving the 24 pin in and just test the cables to the CPU and GPU etc etc if there is no volts coming through then that may indicate that the CPU (or the GPU) is getting no supply.

Do you get any beeps at all on power up? Maybe the RAM is shot might be worth trying this.

MEMTEST

http://www.sevenforums.com/tutorials/105647-ram-test-memtest86.htmlthis one you will need to make a bootable disk set the BIOSto optical (or USB if preferred) boot the machine and let it run for at LEAST 8 passes unless the errors come upstraight away. Takes a fair time to complete and some leave it runningovernight.

If you do get errors and have morethan one stick then you will need to test each one separately and maybe even inthe separate slots.

 

[Shabakthanai]

It was only a matter of time before it kicked off. Going to be a long 4 months until I can afford it. Shall I mark as solved or leave open for a few month until I get it fixed?

Not sure this will help, but I would try it before I replaced the Mobo. Shutdown and disconnect the power cord. Wait for about 20 seconds.

Remove and replace the CMOS battery and restart your computer. This will start you off fresh as with a new build.

It is a lot of work, but not so much if it works. Hope this helps.

 

[Wandering one]

For what it is worth I had the same thing happen a couple of years back. First thought was PSU. Didn't help but needed better on anyway. We were travelling around the Yukon and Alaska at the time and really needed the computer. Desperation says WTF can't do any worse,(maybe) so I tried removing all the cards on mobo, tuners, video etc. Obviously with video out nothing is visible but lo and behold, a miracle. When powered on the HDD active light is keeping its flash a second seek light going. Put cards in one at a time and it was the video card killing it. Found new video card (this part hurt) $125 for a cheapie that cost $37 in Calgary but beggars can't be choosers and it worked perfectly for the rest of the summer.

This may or may not help you but the price is free. Good luck,
Art.

 

[Alpha]

I just dealt with a power switch problem on one of my computers. To test if the motherboard headers were working correctly you can jump the circuit without the power switch (carefully with a screwdriver). I fixed the issue by going to radioshack and buying a momentary power switch. Any momentary power switch should do because all your doing in connecting a circuit. I cut off the old switch and wired on the new one. Computer works great now.

 

[cedsays]

It's been a few months but I'm back! I've finally purchased a new motherboard and CPU. My problem now is the hard drive isn't booting. "reboot and select proper boot device. I've tried everything to get into BIOS but no luck. Would I need to purchase a new hard drive to work with a new mobo/cpu?