HP Pro Desk 600 G1 SFF Video issue

Recently changed jobs and now have much broader job duties. Part of that was purchasing and deploying new desktop PC's. Our agency needed dual monitors for all users and we ended up choosing the HP Pro Desk 600 G1 SFF. It has on board VGA and 2 Display ports as well. We planned on using a DP-VGA adapter to be able to use our existing VGA monitors without having to replace all the cords with DVI or get a DVI adapter to couple with the DP-VGA adapter. We discovered though when we'd reboot with both the VGA port and one of the display ports in use that both monitors would just go black, still had the blue light on the monitor like the monitor was awake but it had no video signal. Powering off the computer and unplugging the Display Port monitor would allow the VGA monitor to work but having them both plugged in did not work.

We had the newest drivers for the system from the HP website as part of our build as of the date of this post and all windows updates for Win 7 x64.

We had disabled secure boot on this HP and enabled Legacy BIOS mode to be able to boot from a USB drive for our MDT deployment of Windows 7 x64

The fix:
Enter the BIOS using F10 while booting. Goto the Advanced menu, Option ROM Launch Policy and set Video Option ROMs to UEFI Only. F10 to accept change. Save Changes and Exit BIOS.

The first time the computer rebooted into Windows 7 X64 it blue screened and rebooted automatically. Subsequent reboots were fine and having both monitors plugged in worked fine thereafter.

The computer I'm looking at and trying this on right now has a BIOS version and Date of L01 V02.18 9/9/13.

------------------------------------
Update

After mixed results as I tried to image more of these desktops I ended up contacting HP support. They had me update the BIOS to L01 V2.23  which in most cases resolved the issue. Some instances I had to clear the CMOS by holding the button down for 5 seconds on the mother board.