Hi, my bro's PC got a new case. I unplugged everything and we put it all in the new case. We pushed the button. It smelled and kept beeping three times. I kept fiddling with the RAM, and it stopped. We booted up and my brother wasw singing "hallulujah£, then I opened the CD drive, my bro was like "is that the midtown maddness CD?" and opened it again. Smoke was round the back and comming from the CD drive. I switched it off, and we checked everything. The only thing that smells is the CPU fan, which I've checked and is working, although, the fan sucks in, so that could be the prob. The only thing thats changed is: The case, and the PSU, which was second hand after a friends PC blew and hasn't beeen tested. But the PSU doesn't smell.
It could be your friends PC blew because of some fault with the power supply and by using it you have damaged yours as well. Only suggestion I have is try your old power supply which I presume you still have and see if anything else is damaged.