Computer boots, but nothing displays

About two months ago I detected a defected piece of ram in my computer and decided to send it in for a replacement. When I removed the defected piece of ram and moved the working piece of ram back into the first ram slot, the computer would boot, all the fans would run but nothing would show up on my monitor. I then inserted the defected ram back in and still nothing. I then removed my graphics card and tried to run it off my motherboard, still nothing. After reading some articles online I decided to send my motherboard, CPU and ram back for for repairs under warranty. I now have all the pieces back together, and reinstalled them into my case and found that I have the exact same problem. The computer will turn on, fire up but nothing will display. I have discarded my graphics card as a cause because it was working fine two months ago before all this mess started. I haven't been able to test another graphics card because the only extra graphics card I have is a Radeon 9000 pro which doesn't fit in any of the sockets on the motherboard. I am completely out of ideas and any help would be welcomed. Thanks.My computer is a self built:Gigabyte Motherboard2GB of Adata RamAMD processor Sapphire HD 2600 XT graphics card450W Sunbeam Power Supply Computer boots, but nothing displays
i had same problem with my old comp. i had a burned out CPU. Computer boots, but nothing displays
It has nothing to do with your VGA, anyways Ive had that same problem and it is always a bad RAM try taking out one and then the other one to see if which one is borken that shoould be the problem IMO
I have tried removing one piece of ram and trying to boot the computer. I still get the same problem. When I remove the other piece of ram, still nothing displays.
Take out all the RAM, then turn it on. See if it beeps at you.
Check the POST beeps then go here :Dhttp://www.pchell.com/hardware/beepcodes.shtml

Unfortunely, this computer has never beeped during startup. It would typically run fine a couple months ago before it stopped displaying anything. I always figured there wasn't an internal speaker on the motherboard.
Is there a power connector on the MOBO for a speaker? You can buy them for around 50p. Normally 3-4 pins I think and says 'spkr' next to it :)
Does the hard drive disk light in your case turns on?If not try changing the mother board to hard drive cable with a new one.I had a similar problem a couple of years ago with an IDE HDD, when hitting on button the fans would start the on-light of the case turned on but the computer couldn't enter POST, the problem was a defective IDE cable. Edit/ Wait, does your pc enter POST or doesn't? LOL, i was giving you a solution without the proper info, and in any case if you have a SATA it may not work the same way as IDE.