XPS 8700 + Nvidia GTX 570

I just bought a new XPS 8700.  I installed an SSD drive, loaded all my apps and files, and everything went smoothly.  Then I replaced the PSU with a 650W supply and installed an Nvidia GTX 570 graphics card (harvested from my old Dell Studio XPS) to replace the Nvidia GTX 745 that came with the PC (which has about half the horsepower of the GTX 570).

When I first booted it up, I got no video at all via the DVI port.  So I hooked up the monitor to the VGA and was able to use that to download/install the Nvidia drivers for the GTX 570.  Then I was able to get a display over DVI.  However, two things are still amiss:

1) The Sleep option has disappeared from the Power options.  I know the GTX 570 supports sleep mode because this worked fine when I had this card installed in my Dell Studio XPS.  I've scoured the forums and other Internet sites and cannot find a solution that re-enables the Sleep option.

2) I get no display output over DVI or VGA while the PC is booting up.  So if I try to enter the BIOS by pressing F2 during boot, the PC enters the BIOS setting mode, but I can't do anything because there is no display output.  I've read that you need to disable the on-board display in the BIOS to resolve the Sleep problem, but it's kinda hard to do that when you don't get any display output.

Does anyone have any suggestions?