Hi, Last night i was watching a movie on my friend's pc and then suddenly, sparks and smoke came out of the back of the PSU... So, guessing this was not some kind of a very good thing, i shut down the PC and i haven't turned it on yet. Today i opened the case and everything seems to be normal, even the PSU, but i dont think it's safe to just switch it back on is it? If let's say its is the PSU but the rest of the system's also screwed, will it be a good idea to put in another PSU from another pc to check? Thanks in advance.

Try another PSU is the way to go..

You could pull the PSU, jumper the MOBO power connector to emulate "power on" and test it with a volt meter. If it tests OK, the sparks may have come from elsewhere and you could be putting another PSU in harm's way.

Failing power supplies are common, and that is the most likely the thing you have just experienced. If I were you I would NOT turn on the computer. Check your PS. See response 4 in this: http://www.computing.net/hardware/w...

If there were sparks and smoke coming out of it, don't turn it on until the problem is fixed. If you do, you're likely to only cause further damage to the system or start a fire. Smell and look for burnt parts around the PSU and inside of the case, if there was much smoke you might be able to detect where it came from. If you can't tell, I suggest replacing the PSU as a precaution regardless before booting up again. James

Well i just put in another PSU and the PC works fine again, all voltages are ok etc... So as it turnes out it was the PSU, which was no more then a year old btw. And to make sure the old PSU was the problem we connected the wires with a U-shaped jumper to power it up without a motherboard, As a result; more sparks, smoke and a very nasty nasty smell... Thanks again.

"So as it turnes out it was the PSU, which was no more then a year old btw." It was probably an el-cheapo. Does he have an emachines computer? You're lucky it didn't damage something else. Decent power supplies don't cost much more, are often warrantied for 3 years, and even if they do fail they are a lot less likely to damage your mboard or components connected to it.