Well, bad news first, the CPU could possibly be history, or the motherboard, but let's not jump to any conclusions to soon. Best thing is to start taking stuff out. IE, strip everything out like PCI cards etc so you've just got your graphics card, motherboard, drives CPU etc left. With just the bare minumum of stuff in it, try and start it. If it starts then start putting bits back 1 at a time till it doesn't start, then you know the problem bit.
If you're down to just the bare minimum of stuff and t still won't work, try reseating the graphics card just in case it's that. You might also want to check all the cables and connections to make sure power's getting to where it should be going.
Still no joy? You said you tried clearing the CMOS, well, try it again, but take the battery out if possible and leave it out for about 15 minutes then stick it back. Still nothing? Try and beg/borrow/steal a similar CPU from someone, stick it in see if it boots.
If not it's most likely the motherboard. Not a very accurate diagnosis I'm afraid but hopefully you should narrow it down from there. The beeps it makes usually correspond to a specific error code, so it could be worth checking in your motherboard manual or on the manuf's website what the certain beeps mean. However, if your motherboards gone poof then they could be a bit misleading.
Hope some of that helps you diagnose the problem! Good luck with it!
