This sounds like a bad power Supply. The "loud noise" you claim the CPU is making is actually the CPU fan running wild. This tells you that the 12 volts is still present in the PSU, but nothing more. There are other voltages that have to be present for the board and CPU to function, if they're not available, then a blank screen is usually the result.The power supply should be substituted for a know good unit, you really can't get a fix on the problem until this is done anyway.
Emachine computers have trouble with bad motherboards, by judging by the number, yours is a fairly new one, so that probably isn't a factor here.