This is a weird one.. I have a FHD AGI260T 26z monitor connected with DVI-D (computer) to VGA (monitor). Computer is a Cisco VXC 6215 box running Debian, Ubuntu or whatever live usb. Problem with all these versions is the same: when booting with monitor connected, screen is blank.
But when I boot from a different external HD ready monitor (DVI-D to DVI-D) and switch the monitors when I see Linux running, the first monitor IS working. Right up until a reboot.
I've tried to set different resolutions with GRUB, but the resolution remains the same, I cannot see what it is, but it appears 1024x768