Solved PC died while it was running and now it is not powering up

December 27, 2011 at 09:06:27
Specs: Win 7, P4 Core 2 quad / 3 GB
Hello there, I've seen a few similar questions but I just want to be 100% sure about this.

How it happened: I was watching video and all of a sudden the screen blinked twice, the video 'shrank' real fast and then the whole PC shut down.

Any changes made recently? - No changes were made to the PC in last one year.

PC Details:

Acer Aspire M 5641
Pentium Core 2 Quad
RAM 3 GB (1GB+2GB)

Troubleshooting done:

I've built a pc or two before so I had a fairly decent idea on what's going on. First I checked the power supply. Found it to be a cheap 250W Lite-on PSU. I should've changed it long back! I took out the PSU and shorted the green wire with the black one to simulate Power ON and then checked with a multimeter. There was no output and the psu fan was dead.

So I bought a new PSU, a Cooler Master ModXream 500w. I tested and it works fine. Hooked it up with the PC and tried it - but it was still dead. I took out the motherboard and gave it a thorough clean-up. It was quite dusty, despite my occasional cleaning.

I hooked up the motherboard with the psu and had only the RAM installed. I pressed the On button but nothing happened (the fans also weren't moving also)

I took off the RAM and tried again. No result.

I traced the two pins which are shorted when I press ON button. With multimeter, I checked if the pins are shorted for real and they are.

I replugged the psu and then shorted the two PINs myself using a paperclip to simulate the 'switch on' but still no results :(

I didn't see any burn mark or odd smell.

Checked the cmos battery with my multimeter and it;s alright too.

My back is at the wall now. Any idea how to be sure if the motherboard is gone or the processor?

Appreciate your expert advice on this, thank you so much!!

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December 27, 2011 at 09:34:57
✔ Best Answer
When a power supply blows, it's not unusual for it to take out other components along with it.

If you're attempting to benchtest the board outside of the case, all you need is the power supply connected to the board (both the 24-pin & 4-pin), CPU w/HSF, one stick of RAM, keyboard, video card (or onboard video), & monitor...nothing else. To fire it up, just momentarily touch a screwdriver blade across the 2 pins that the power button would connect to. I'm unsure what you meant about using a paperclip, but if kept a solid connection across the 2 pins, you may have damaged something. Touch & remove, that's all that's required.

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December 27, 2011 at 09:44:02
Thank you Riider, for the quick reply.

For the benchtest, I connected the motherboard with the psu only (24pin + 4 pin), CPU w/HSF, had both sticks of RAM and later removed them both.

Didn't have any video card or monitor connected because I just wanted to see if I get any beeps or fan movement that'd tell me that the motherboard is up.

Clarification: I didn't touch the pins together more than 1 sec (max) I used the flat of a screw driver and later the round side of a paper clip (it's easier to touch those two pins using the paperclip - less chances of touching other pins) I did just as you said, 'touch and remove'

So, is the motherboard gone or only the CPU?

Thanks again Riider..

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December 27, 2011 at 11:04:28
Since you plugged the mobo in and got no sign of life, I'd venture to say that the board is fizzed. If the cpu was shot, i would think you would at least get the fan to spin. And no sign of life when you short the pins is an indicator that the board isn't getting any power. Just my opinion.

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Related Solutions

December 27, 2011 at 20:34:57
I certainly sounds like the cheap power supply took out the motherboard with it. If you have another computer to swap out the power supplies and confirm that the new power supply works as you think it does in the other computer and the working power supply does not power up the motherboard in your benchtest, then you have confirmed this for sure.

You have to be a little bit crazy to keep you from going insane.

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