0ld G5 Power Mac monitor is partially dimmed, and flashing 3x, but computer is working fine !

I have an old G5 I use as my CAD machine (2009 model at least). Came to the studio this a.m, and the monitor is partially dimmed(top half, and the power button flashes 3 x every 5 seconds or so.

The computer is working fine !! It's been a beast, and I never felt the need to replace it.

I've re started it, but same issue comes back.

Question:

is this a low battery issue ? I can't even remember when I changed it last, if ever.

Could the monitor be dying, and I need to find a replacement ??

Bad monitor cable ? I've unplugged it and cleaned it and re installed it, no change.

As I stated, the computer itself is working per usual.