[Halcyon]

The first to always check when you get diufferent beeps at POST are to see if you still have your motherboard manual as it is often explained in there.
eg. 1 beep = this, 2 beeps = that.
If you dont have the manual, make a note of the motherboard model and number at POST and google it. You should be able to find it online somewhere.

As has been suggested, reseating the cards and checking RAM is correctly in place, testing with only minimum components and then reseating them one by one is a way of finding out the problem.

Before binning that Hard drive, you could have tried it out in another machine.