Perfect, long time runnung system and BLAHHHH...Help!

Dear Felow brothers, this is my first post, I Have been seiing hard for a couple compamines, some of you may have heard, TCWO (aka Thompsons Computer Warehouse) and BCD2000 and a nother no one cares about....anyways I have a Asus P4T-E with 4 x 128mb PC800 Rambus mem sticks and a P4 1.6 running cool at 2.2ghz, 400w PS Antec., CDRW, DVDRW, ATI Radeon 9550 128DDR...been working great for almost 4-6 years (sorry lost count).....BUT herers the the problem one day I boot up all my case lites lite up and I hear all the normal sounds but no video (Samsung 21" Syncmaster 205BW) I tryed changing PS's. no deal, the same thing even happens even when I leave the hard drives unpluged from the ribbion. And what another coincidence I was givin another gatway compouter with Rambus and it does the same thing............CAN ANYONE out these throw me a bone I can usually fix most problems selling hardware for almost 9 years, But I'm stumpped...any advise would be greatly apreciated!

Thanks,
BEN

Also, I almost forgot , there is no beeps at all, no sounds, just not post and it just stands there with with nothering but a blank screen.

Thanks,
Ben

Also, when I pull the IDE cables and Video Cable to the monitor, it does the same thig, just all the lites in my case case work and nothing else...I assumed it was the MB or CPU, but I wanted to hear it from some others that are still in the seen unlike me,, back in the day I could figure this out over the phone within seconds lol

Thanks for all your help,
Ben