The obvious question to me is, have you tried another monitor?
I received a brand new Dell 540 Slim Studio with Windows 7, without a monitor, as i still have a good working Gateway VX930 monitor.
When I tried to boot, it passed the Dell Logo (Initial Power Up), then displayed the animated graphic, "Resuming Windows", and then in about 5 seconds, my screen went blank. The hard drive indicator light continues to flicker though, implying the drive is active.
I have no other peripherals connected, other than the keyboard and mouse.
I was unable to initiate the One-Time Boot Menu (F12 at the Dell logo) to run diagnostics, or to initiate the Safe Mode (F8), due to no response when using the function keys. Keyboard does have power and seems to be connected, as I am able to see the Numeric Lock or Scroll Lock indicator lights when pressed. I also connected my older working keyboard, with the same negative results.
I spent an agonizing 2 hours and 48 minutes total on the phone, talking to 10 different Dell Support Technicians, with half of them who could barely speak or understand English. After explaining my problem, each one would put me on hold and pass me off to another technician, only to have to repeat all the details of my problem again.
They finally gave me two choices, that I could bring my computer to a service store to have the motherboard replaced (they didn't say that was the problem, only that it would be replaced), or they would send me another computer and I would have to send the old one back. I decided on the latter.
Today, after a week, I received my replacement computer, plugged it in, and it has the exact same problem.
Anyone have any ideas? I dread the idea of having to call Dell's Technical Support nightmare again, I would rather stick needles in my eye.

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