yeah, if it smoked, it's toast. chips don't survive being smoked. I have toasted a a fair amount in my youth making electronic gadgets and circuits. maybe the Voltage Regulator Module on the motherboard went bad (it regulates power to the proc, and if a cap[acitor] busts for whatever reason, age or defective manufacture, it could very well frap a cpu...)
read this article. cpu probably overheated. or it's just plain overvoltage. could just be overvoltage, since usually the cpu has a built-in thermal shutdown PROCHOT flag and sensor that protects it (unless its defective, or your OS is hosed because possibly the filesystem is corrupted and it refuses to shutdown).
or your fan died. or the fan stopped due to dust buildup (I call them dirt clods). I have heard these 2 aren't sometimes fatal because of PROCHOT, which may spare the cpu.
best thing to do is replace mobo, PSU, RAM, and proc. essentially you are getting a new machine. that mobo runs just about everything, and who knows what it was frying. hard drive? might be OK. RAM could be OK, but the new mobo will probably require different RAM. :-/ would be an excuse to get a case with better cooling.I suggest the corsair carbide series. I like the 500R. if you have high psu needs, the pc power and cooling turbo cool 860 should do nicely.
good mobo mfr's: ASUS, ASROCK, MSI, maybe GIGABYTE.