G'day ardfoe8, that is a nuisance, in that you have changed the memory position and it beeped would appear to indicate you are close to working, all the fans operating also support this.
What is the video system is it on board or a card, can you try it with a simple pci video card if you are using an upmarket one.
Keep the minimal system until you get it to post, and video on your monitor.
Do not touch anything or replace any cards unless the power lead is removed from the machine.
Make sure all drives are discon from power.
Are you using a new case and power supply, if so what is the power supply wattage?
Under normal circumstances you should get some monitor activity and led condition change if the power, processor, memory and video are good. Hopefully with one short beep.
So one of those items has a problem, (including the motherboard) so you need to evaluate by interchanging one at a time.
In that you got a beep it is likely that your processor is OK. I imagine you have properly fitted the processor with a heat transfer substance of some kind.
If it was a heat transfer patch do not play removing the thing they are really only good for one use.
Low voltage can have odd effects and cause confusion.
Memory can also kill the thing, under no circumstances plug any memory in the mother board while live power is connected.
You may need to carefully try items in another machine but use absolute caution.
Usually what happens is that people unplug video cards while the power plug is in, without realising that the sockets are powered anytime, this commonly kills video cards, and often takes out mother boards.
So you will have to coax the thing into life, I usually start with a simple PCI video card and once the thing is operating satisfactorily introduce the more complicated upmarket video card, it really pays to do this and saves time also, avoiding odd problems.
Double check all the pinout connections on the corner of the board, hddled and all those, ensure that are all connected to the correct terminals and around the right way, coloured wires usually are the plusses. Incorrect connections can stop operation, sometimes the board markings are wrong, use your manual to confirm.
Cheers, qldit.