Bizarre self-build problem

Hi everyone,

I have a bizarre problem with a PC I built 6 months ago. Here are the specs:

Asus F1A55-M LE
AMD A4-3400
16 GB RAM
Asus Radeon HD 7770
Dual boot Windows 7 and Ubuntu 12.04

This build worked perfectly until 2 weeks ago. One night, I was just using a web browser in Windows, and the PC blue-screened with a system service exception message. After that, it would not boot up - at all.

When I turn the power on, the fans spin up, but there's nothing on the display and no POST beep. There's also no power to my USB devices (no light on the bottom of the mouse, nothing when I turn Caps Lock on). I've tried eliminating everything I could. This is what I did to try and fix this issue:

Take out everything unnecessary, and just use on-board graphics.
Switched the RAM for stuff I know works.
Clearing the CMOS settings.
Using a different power supply that I know works.
Taking everything out of the case and setting it up inside a cardboard box, just to see if anything was shorting against the case.

Here's where it gets weird. I assumed it was a faulty motherboard, so I returned it to the retailer. They tested it, confirmed it was dead, then gave me a replacement.

The replacement lasted an hour, then exactly the same thing happened. I tried all the above diagnostic ideas on the new motherboard. Same situation.

I assumed there was just something in my system that the motherboard didn't like. In frustration, I bought a different motherboard (ASRock A75M-HVS) and set it up. I turned on the system and went into the BIOS to set it up. Five minutes in, the system froze. I rebooted it. Guess what? Nothing on the display, won't POST and no power to the USB devices.

So it's definitely not the motherboard. My instincts are telling me the CPU might be dead. Anyone have any ideas what I could try?
7 answers Last reply
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  1. There's a possibility that your PSU is faulty and every time you plug a new motherboard into it, the PSU kills it, certainly an odd problem though.
  2. Thanks for replying.

    My PSU is a cheap 500W one that came with the case. I think it's destined for the bin. The other one I tested with wasn't any better. I'll get a better PSU. Best case scenario, the motherboards aren't dead, just not getting enough power.
  3. lexx_koto said:
    Thanks for replying.

    My PSU is a cheap 500W one that came with the case. I think it's destined for the bin. The other one I tested with wasn't any better. I'll get a better PSU. Best case scenario, the motherboards aren't dead, just not getting enough power.


    Go for a Seasonic, Corsair, XFX, Antec to name a few. A weak powersupply can cause all sorts of problems and a bad power supply can damage/kill every component in your computer that takes electricity.
  4. I agree. PSU problem seems likely.
  5. this is why you dont use cheap psus. they can cause serious amounts of damage.

    people think because the psu isnt hardware that makes your pc faster, you can skimp on it. let this be a lesson to you, that you really shouldnt
  6. see if it will boot with no graphic card
  7. Before you throw the PSU, if you have a voltmeter, check the voltage you're getting across the green wire and any black wire, could show if you're getting too high a voltage. And yeah investing in a good PSU is a good idea because it'll last you ages if its well built
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