"A few beeps" is the message telling you the problem. The Dell service manual tells you what the beep sequence means. It also tells you what the LEDs mean. You can also find this stuff on:
...

Did your C++ program perform any low level function, overwriting an unfortunate disk sector?

I think we'll wait until you've got a PS/2 keyboard attached and you've tried a few more things. Are you sure it was the Northbridge chipset fan that has the problem? If it's the Southbridge that...

It could be either or both of two problems

1/
PSU by your own estimation is not doing the job

2/
A glitch on the latest PSU hosed the mobo.

We should really be diagnosing this with the...

Great. Please mark this thread as solved.

Sorry for the glib reply - it's bust and needs fixing. Not much we can do here unless there's a Tosh geek here acting as a repaor manual.

if it's overheating, Windows is frozen and cant respond...

If your laptop screen is bust the controller might still think its OK (depends on the bust). if that's the case, then pressing the appropriate function key to go to the attached monitor might work...

Is the power block warm? If not, it's failing to charge the battery and you're out of charge.

Looks like some sort of pwer problem as I think you've judged. See page 15 of your manual for some...

Aren't you supposed to clock the new CPU at the proper speed? Have you got jumpers on the mobo to do that?

And is all in order with the FSB speed?

I wouldn't have done what you've done without...

If I understood you correctly, you closed the lid for an hour with the PC ON, not in standby.

Could it have cooked itself and you're now suffering the consequences?

Maybe it only cooked the LCD...

Very difficult at a distance to diagnose. But it seems there is a common cause; unlikely to be the PC, so it's possibly the mains. Ant-surge devices need really good chokes to work and there's...

I don't see how the CPU's damaged if it does any stuff at all. Could be a short on the mobo which vacuuming could remove.

These things usually spell the end for a particular PC.

Often the user Administrator is defaulted to no password. try it.

Otherwise there are utilities available (google it) to reset locked accounts.