graphics problems, even in BIOS

[sapi]

Three things you need to try sapi.

First, try a different monitor that you know is working.

Check. The signal is identical over VGA to this monitor as it is over VGA to a CRT I had lieing around in another room; it's distorted during boot (the black background of the BIOS POST checks had white flecks on it), and testing PCLinuxOS on this computer over VGA showed massive distortion.

Do VGA connections have higher tolerances to signal fluctuations or something? Because I'm struggling to come up with a reason that the VGA input would work, shoddily, while the DVI didn't (by the way, by 'VGA input' I really mean a VGA-DVI converter sitting on my usual output)

Second, swap out a different video card that you know is working.

I don't have a spare PCIE one unfortunately; certainly that'll be my first instruction once I've got it down at the shop tomorrow

Your symptoms sound very close to what happened to me in the past when I had an older CRT bite the dust, so my guess would be your monitor is going bad.

I would have thought the same actually, except that the problem first appeared after a graphics driver related BSOD, and the image isn't good on the second monitor (I mean, it's as readable as it is now, writing from my primary monitor over VGA...at 1280x1024 on a widescreen ...but it's still not as good as it was). The collections of white vertical lines over the BIOS background are what worry me