The PC that had this Nvidia GTX 670 graphics card in it refuses to start any recent variant of Linux I try on it via a USB live installer, it shows the boot/BIOS and splash screens OK but ends up with a black screen or garbled graphics. Still not sure if it's a hardware or driver issue, but...
This is the side of the GPU PCB facing upwards in the tower:
Looks like thermal grease dripped all over it from somewhere. Related?