Question TL:DR- Water damage, what's broken CPU or motherboard?


Jun 27, 2014
Hi, so before I get into the tale of diagnosis attempts the specs of the build are/were:

i5 8600k cooled by a be quiet shadow rock LP
GTX 1070
Asrock Z370M-ITX/AC
Samsung 850 EVO+ Western digital HDDs

Last year I moved house, it turned out to be damp. I left for the weekend came back to turn it on and was greeted by a puff of smoke from my power supply which at the time was a CX600m. I replaced it with a EVGA 650G, this works. Now that I'm back from uni I tested it in an old pc. My GPU displays from this old pc and my storage is detected by it (WOOO!!!). The last few days I've been playing around with different possibilities. Just trying to boot as is results in hard drives powering on, all system fans spinning. I do not have any beep codes or LEDs coming from the board. Following this it turns off after around 20 seconds. If I remove the CPU, the fans stay on. But obviously no boot and no error codes. I don't have access to a compatible CPU or a motherboard with the same socket type to test.

Does anyone have any diagnosis suggestions or experience with a similar situation? Or any way of determining if it's the motherboard or CPU or both?

I want to repair this for relatively cheaply student and the current world situation encourages frugality. So I'm weighing up buying a second hand 8400 or 8600k. Trying it and then replacing the board if it's also dead. Or getting a Ryzen 5 2600/3600 and a B550 board which will end up costing the same if I replaced both.

Thanks for your help.
A guy who misses playing Sid Meier's Railroads more than he should do.
Without trying a different motherboard or CPU. I don't see how you could definitively say one, the other or both. However, the motherboard is a much larger target with no protection. While the CPU is much smaller, covered by a heatsink and shield by the socket. Water could get to it but it is far less likely.

You've replaced the PSU. Have you ruled out everything else RAM, GPU, &c? You can visually inspect the motherboard and look for scorch marks. You can also give it a sniff test. Just to confirm before trying a replacement.

As the smoke came from the PSU. When it surged. It could have taken out the motherboard and CPU.

You could always just look for a cheap open box H310 motherboard and try it out. If it doesn't work return it.

Another option is to sell the pair on eBay for parts or repair only, condition unknown and a brief description of the problem. People will bid on it and you'll get something for them.