Precision T5500 no video

Summary: My T5500 dual processor refuses to show anything on the screen. I have tried 3 graphics cards, removing all but 1 RAM stick per processor, CMOS reset.

Detail:

I have 3 computers and a two-machine DVI KVM switch. On one end of the switch is a Windows 7 PC. The other end of the KVM switches between the T5500 and a custom assembled machine, both running Ubuntu. Usually the custom machine and the Windows PC would be on the KVM and the T5500 would run headless. The Ubuntu was set to auto login and start Teamviewer so I could access the GUI on T5500 and run jobs. This setup worked fine for months until I needed to switch the monitor to the T5500. All machines were shut down and KVM switched to T5500. No signal, not even Dell logo.

1) First thing I tried was to replace the high power nvidia GTX 560Ti with a modest graphics card. Did not help. Then I put the original NVS 590 card in, which didn't help either.

2) The machine was booting fine and loading the OS and I could see the system working in Teamviewer but nothing on the monitor.

3) I connected the monitor directly to the T5500 and rebooted. No change.

4) I followed the manual to clear CMOS. I took out the jumper from PSWD and put it into RTCRST, waited 10+ sec after connecting power, replaced the jumper and started the machine. Now it doesn't even boot Ubuntu it seems as it does not come online on teamviewer any more. The LEDs are either 1 2 3 on or they all turn off with the power LED solid green.

5) It has two HDDs. If i remove one, it will stop at two beeps. This is just like it would stop during post at "drive not found error". It does not beep at all when both HDDs are attached normally.

6) I had 6 RAM sticks for processor 1 and 3 for the second processor. I removed all but the ones in the DIMM1 for each. Still same.

Any pointers will be greatly appreciated. KVM is fine because if I switch the cables to my custom built machine, I see the Ubuntu GUI fine there.