I have a Gigabyte GA 790FXTA-UD5 motherboard. I spilled ice cream on the case and it went through the top vent and onto the motherboard. The monitor went immediately into stand-by (uh-oh!) and I switched the power (to the PSU) off at the mains socket. I opened the case up and used a moist kitchen paper towel to clean up the ice cream. I allowed it to dry and sprayed with compressed air for good measure.
The behaviour of the machine was really inconsistent from this point on. Most times when I turned it on, it reset itself every five or so seconds. Sometimes the CPU fan would come on but most times it wouldn't. I took out one of the graphics cards and tried it and it booted to Windows. I shut down and put the card back and then it wouldn't boot again. I removed the card and it still wouldn't boot. I left it unplugged for a while and later booted to Windows but it shut down spontaneously. I sometimes used the Clear CMOS button but wish I hadn't because now, even though I've booted and loaded Windows, it doesn't recognise most of my hard disks - it only recognises my system drive (SATA SSD). I have some regular SATA HDDs but the BIOS doesn't detect them.
I've uploaded photographs and zoomed in on the area that was shorted by ice cream. It was vanilla, in case you're interested and yes I know I'm stupid for letting this happen and it's why I don't have nice things (apart from this computer!).
(click to enlarge)