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EDIT - Turns out coffee got into the case through the top fan... dripped down the back of the motherboard... Ho hum....

This morning my cat decided to chase absolutely nothing across my desk. This meant my morning coffee fell victim to a rampaging ball of fur.

I've got a very solid desk, which the computer is underneath. Sides and rear are protected. Coffee didn't hit the tower at all, just went all over the desk and carpet. Avoided the mouse and keyboard.

However i've had a wireless QI charger on my desk for a little while, connected to a standard USB2 socket on my PC, and this got soaked. Almost immediately the computer switched off. Now it won't switch on again, even at the wall (it's usually connected to an energy-saving power-strip).

I had thought that a computer couldn't die if one of the USB peripherals broke. Please say i'm still right and that there's an easy solution. Without my morning coffee i'm not working well enough to be able to solve this myself...

Scott Penn
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    The USB ports *should* be protected against shorts and it might be that there is a resettable fuse that just needs a bit of time to sort itself out. I recently had a similar incident with a rampaging ball of fluff pouring a glass of water into my keyboard and all I suffered was a single solitary blue screen as the USB controller decided it wanted a holiday for a moment. Try unplugging the computer from the wall for a few minutes to allow fuses and supplies to reset properly. – Mokubai Apr 22 '15 at 07:27
  • Just took out the power cable and waited for the motherboard light to go out. Plugged back in, hit the 'on' button and the soundcard light flashed (X-fi titanium) and the mobo light re-appeared. Nothing else... – Scott Penn Apr 22 '15 at 07:27
  • You might need to give it a couple of minutes for all the various power regulators to shut down and reset themselves fully before restoring power. Unplug all the USB devices and anything else you can before plugging it back in just to see if any of them have been soaked without you noticing. – Mokubai Apr 22 '15 at 08:12
  • Thanks Mobukai - still no joy it seems even with only the power cable plugged in. The CPU fan WANTS to spin up (gives a little twitch)... – Scott Penn Apr 22 '15 at 08:18
  • Complete disassemble done. Seems there was coffee down the back of the motherboard between the mobo and the backing plate. How screwed am I? Is this a new mobo/CPU/PSU job? – Scott Penn Apr 22 '15 at 08:45
  • Its next to impossible to say just how bad it could be. You could be lucky and it just needs to dry out and everything could be fine, or at worst you could have shorted 12v to the 1.8v CPU line and blown everything between the CPU and PSU. It could be good or bad. Get it dry first, see if it still does anything and work from there. It would be worth editing this new information into your question. – Mokubai Apr 22 '15 at 09:18

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I had thought that a computer couldn't die if one of the USB peripherals broke

Not true. The coffee probably shorted out the +5V pins in the USB stick. Just like the breaker box in your house, an electrical short can affect everything on that circuit. Every device in your computer connected to the +5V rail from your power supply likely "felt" the short.

If you're lucky, it just damaged the USB port or the wire connecting it to the motherboard. I assume this is a front USB port the device was plugged into. Open up your computer and follow the wire for the port to the header on your motherboard and unplug it (hopefully it's not a ribbon cable for all your front panel lights and buttons). See if the computer boots with it disconnected.

You may have also tripped a fuse in your power supply. Take the cover off it and see if there is any way to reset or replace it. NOTE that even while it's unplugged your PSU can still give you a jolt, so be careful!

Wes Sayeed
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  • Thanks for your suggestion Wes. Unfortunately it was a rear motherboard USB port (only one of my front one works and I like to keep it free for USB sticks) I took the side off but can't see any fuses on the PSU. It's a Modu 82+ if that helps at all. There IS however a green light on the motherboard... so power's getting there somehow... – Scott Penn Apr 22 '15 at 07:18