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Although it may seem I have merged two questions into one here, I feel they are directly related and thought best to get all the info out there for diagnosis.

I have issues with a new PC I've just bought and built. FWIW, specs are;

  • Asus H81M-Plus
  • HyperX 4GB DDR3 (1 x DIMM)
  • RM850i
  • Celeron G1840

I built the machine (out of the case), powered on the PSU at the wall, green LED lights on MB (manual isn't clear but this seems to be normal behaviour). Pressed the switch on the case (wired the power button from the case onto the board) but nothing happened. Thought the button could be dodgy so proceeded to short the power button pins - still nothing. When I say nothing, I mean no POST, no video output, no fans. I also tried shorting between the power button + and various grounds incase of a grounding issue on one of the power button pins, still no joy.

It was at this point I realised (the hard way) that the chipset was approximately 1 million degrees centigrade as the back of my hand caught the heatsink. It's not something I've ever thought to check on previous builds but I'm pretty confident that isn't normal. I completely powered down (from the wall outlet) and let everything cool down. I then switched back on at the wall (but didn't attempt to power on the PC) and the chipset again rocketed in temperature right away.

The only other component I've been able to test and prove good is the PSU but hooking it up to an old machine, but that powered up fine. I don't have the spares to test the memory or CPU (however I would at least expect a POST and error if it were one of these).

I guess I am right in assuming that the chipset should not get hot when the PC is turned off. Could it be that the power switch is actually shorted closed, hence the chipset getting so hot so quickly?

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    That sure sounds like a reverse voltage being applied. I hope you got the power off before it actually reached 1,000,000. ;-)
    – SDsolar
    Commented Jun 26, 2017 at 1:03
  • 2
    I think if it reached 1MC then it is time you looked up your home owner's insurance. That is to say. You should claim for the property damage of having a pc motherboard detonating in your house.
    – Aron
    Commented Jun 26, 2017 at 3:31
  • For what it's worth, I have now got a replacement board which works fine. I will try to find out what the problem is when I return the old one, however I don't hold out much hope of the support team actually telling me what was wrong!
    – Jonny Wright
    Commented Jun 27, 2017 at 17:36
  • @JonnyWright: I have same motherboard (ASUS H81M-Plus) with same problems: no power, south chipset and UZ2085G getting so hot. Is this a common problem for ASUS H81M-Plus?
    – C.F.G
    Commented Jul 7, 2020 at 11:07

1 Answer 1

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That sure sounds like a reverse voltage being applied somewhere.

I would think the green lights are indeed a good sign that it is not a direct short.

Time to use your DMM to check what is coming out of the PSU.

But something is wrong, and you know from the heat that it involves power.

It could be something like a misalignment of the CPU on the socket, depending on the type.

I hope you got the power off before it actually reached 1,000,000. ;-)

My rule of thumb is that if it burns my thumb it is too hot and something needs fixed.

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