I took my computer case apart for some dusting/cleaning, and after reassembling, I couldn't get it to power on.  After some fiddling, removing and reattaching power cables, etc., it boots.  The problem is as follows:

After the post screen, I lose video - the monitor goes to sleep, although the computer appears to boot normally.  Resetting it a few times gets me to a recovery menu which lets me boot into safe mode (which gives me video).  When rebooting, I again lose video after the boot.

This occurs whether I am on internal video (z77 chipset and i5-3570 chip, or using an nVidia 970 video card.  Even removing the video card, and uninstalling the video card from device manager doesn't get me video using onboard.  I replaced the card, had zero video from onboard even during post, so I shut down and restarted, and got video from the nVidia card - SUCCESS!  However, shutting down and restarting puts me back in the same boat - no video after post...

Any suggestions?

v/r

Mike