How boned is my desktop PC?
September 11, 2017 3:51 PM   Subscribe

I did a very stupid thing and basically shorted some pins on a SATA power connector while my desktop PC was on and running. There was a spark and a pop and it hasn't turned on since.

This was a PC I built myself from parts so I'm fairly comfortable taking it apart and testing it. I've already tested the power supply using the paperclip method using a multimeter and it seems to be working fine (putting out close to the nominal voltage on the main 24 pin connector). I'm assuming something on the motherboard has popped. I've already rush ordered a new motherboard which should be arriving tonight hopefully. My question is: Is there any way to tell exactly what I've borked and whether my CPU has also been fried? An add-on to that would be whether or not I may have missed something that is going to fry another motherboard/CPU when I plug in the new one? What's the likelihood that one or more of my hard drives, which were connected to said SATA cable are totally destroyed?
posted by runcibleshaw to Technology (9 answers total)
Well, I guess the way I would test this when you get the new mobo is CPU (obv.), power, see if it gets to POST, then just start plugging stuff in one thing at a time. I'm sure there are ways you can test a CPU to see if it's fried without plugging it into a computer, but hell if I know what those ways are.
posted by turbid dahlia at 3:54 PM on September 11, 2017

Best way is to switch out the motherboard and try one old piece at a time if you don't have a ruining machine test parts on.

It really depends where it happened and what power output was.

If the possessor is done, it's done. It most ot likely won't hurt your new motherboard to try.
posted by AlexiaSky at 3:59 PM on September 11, 2017

Remove the motherboard and look over it inch by inch on both sides. Use your eyes and your nose, too-- burnt components have a characteristic smell. Look for solder that doesn't look like it was added by a machine, brown or black marks, or other discoloration that could've come from a very brief flame. Look for capacitors that have the top burst open or the side split.

One could try replacing components-- it would probably be a fairly cheap attempt, but most likely your motherboard is finished. If the damage you find is in the vicinity of CPU or memory, well, that's not good.
posted by Sunburnt at 4:12 PM on September 11, 2017 [1 favorite]

Regardless of what your multimeter might say, I wouldn't trust a power supply that had a short go through it. The pop could be a damaged capacitor which might not show up in a simple voltage read. Especially if you don't see any popped/bulging capacitors on your motherboard, I'd be wary of the idea that your PSU is still functioning normally.
posted by Aleyn at 4:23 PM on September 11, 2017 [3 favorites]

Check all the voltages on your power supply. If you really just shorted a sata power supply cable (I assume it was straight from the PS or daisy chained from another drive) it would be strange, but not impossible, for this to cause a failure on the motherboard.

When you turn it on, do you see lights on the motherboard, does it beep? Your motherboard manual likely has POST codes that might indicate what has failed. If the board does nothing that points strongly at the power supply. It's possible the supply is just failing under load - so a multi-meter test might not show the failure...

If a drive was plugged into the same power supply cable it is possible you will lose the drive, but it will likely be ok.
posted by NoDef at 5:50 PM on September 11, 2017

I'd try to test it with a known good power supply. See my previous question with a similar bent. It can be the case that the PSU will give correct voltages when tested but will not supply enough current under load. If it doesn't work with the new motherboard, and you can't find anything else obviously wrong, I'd try a new PSU before a new processor. (Yes, I learned this the hard way.)
posted by number9dream at 5:55 PM on September 11, 2017

Response by poster: Thanks y'all. I did forget to mention that I do have another working power supply that I tried and it didn't turn anything on. I guess that won't tell me anything about whether the other power supply will destroy my new motherboard.
posted by runcibleshaw at 6:19 PM on September 11, 2017

Bummer! If the PSU still works then your motherboard is probably poked, and I don't see anyway to check a cpu without a working motherboard to plug it into.
posted by Sebmojo at 3:26 PM on September 12, 2017

Response by poster: Follow-up:

Got the new motherboard. Everything seems to work so it looks like the original motherboard was indeed fried but everything else survived intact. Thanks for your suggestions. Just glad my very dumb mistake didn't cost me more.
posted by runcibleshaw at 7:01 PM on September 12, 2017

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