Display Goes Blank

[Modassir]

Hi team,
We are using Pxelinux, wimboot and TFTPd32 to network boot our Litouch (winPE), and the issue is with HP prodesk 600G1 desktop with nvidia G card, where display goes blank.however with internal G card, display works well and I can see the winPE screen.

Checked wDS, and display works well with external G card as well. Please find attached screen shot after which I don't see any display. NOR the display I think excution also stop, because I enabled monitoring on my MDT console but nothing comes up as excution on the system. Update the system with latest BIOS and ME firmware but still issue is there.