I've tried almost all of the options I can find with this problem and I'm really getting frustrated.

Basically, my computer is unreliable starting from having no power on. Fans turn, lights turn on, thermometer turns on, but the moniter stays black -- the moniter power button turns green for a second then GOES back to the usual "sleep" amber color. This has been happening occasionly ever since I got the PC 2.5 years ago. To remedy it I would usually just turn off the computer at the power source and try again to start it (sometimes upwards of 20 times) but I never found a reliable solution to MAKE it work. Usually I'd just end up frustrated and give up, come back sometime later and have it work correctly.

Today I decided to add some more RAM to my PC augmenting my 2 256MB sticks with 1 512MB stick. I installed the 512MB stick, above situation happened. I moved some RAM trying it in different slots with no luck. Finally I tried doing one stick at a time in the slot closest to the processor to see if maybe the RAM was defective. I got 3 beeps when I tried booting and still no screen activity for each stick -- on RAM that was working just minutes before. Finally I got it to start after an hour of fiddling around with it and much to my annoyance I still only had 512MB RAM despite the 512MB stick being in the computer. So I turned it off and tried seeing if I put it in wrong or something and now I'm faced with the same no moniter information but the computer is on.

System:
True Blue 480 Watt power supply
Intel D875PBZLK Motherboard
Pentium 4 3.0 GHz processor
nVidia Geforce FX 5900 Ultra video card
120GB Western Digital WD1200JB 7200 RPM ATA/100, 8MB cache hard drive

Any help would be greatly appreciated.It is probably not bad RAM if it is new so let's don't start there. Go to www.crucial.com and see what memory you needed and compare carefully to what you got, The speed alone is not sufficient. Other specifics on your motherboard possibilities will be shown as well.

There may also be compatibility issues with the existing RAM. Try the one new stick by itself and see what happens. Some boards do better if the largest RAM stick is placed nearest the processor in slot 0.

The fact that you had previous issues as well confuses the issue further.
I've been trying the RAM in different slots and all 4 sticks of my RAM have been setting off the beeps when in the first slot, but when I put one alone in the 3rd slot, the computer starts as it usually does with no moniter. I'll FIDDLE around with it some more and see what I can come up with.

I'd love to run the crucial memory test but I can't even boot my computer to do it :-?What about when you put the RAM in EXACTLY as it was before this manipulation started?Finally after messing around with it I got exactly one stick which when put in the first slot allows it to boot. Any of the other 3 causes beeping. Right now the slots look like this [256][empty] [256][empty]. When I try and put the 512RAM in anywhere in this set up it doesn't beep or anything the moniter just stays black.
The Intel site says:

Four 184-pin DDR SDRAM DIMM sockets
Support for DDR 400 and DDR 333
Support for up to 4 GB system memory

www.crucial.com says:

http://www.crucial.com/store/listparts.asp?Mfr%2BProductline=Intel%2B+Motherboards&mfr=Intel&tabid=AM&model=D875PBZ&submit=Go

What do you have EXACTLY?

Are you mixing ECC and non-ECC?

Did you run Memtest on each stick individually? (www.memtest86.com)

Is there debris in the slots?