Yes wrote:
I posted this in the sister a.c.h newsgroup and got no reply. Hope for
a better response here.

I have an Asus 24" VS248H-P R LED monitor and a PowerColor (Radeon)
HD6750 1GB DDR3 video card. Two or three times now over a six month
period, I noticed that the monitor screen will have a semi-transparent
grey splotch in the lower left quadrant of the screen. IIRC, each time
it happened when I woke up my desktop after it had gone into
hibernation mode. Its shape and color make me want to compare it to
that of a grey cloud. I can see the desktop, but the area it covers is
light to medium grey. At least it's not moving :-)

I haven't experienced this problem before. Is it a prelude to the
monitor or video card failing? If so, which one would be the likely
suspect? What would be useful search terms to use to find out more
about it?

Thanks,

John

I can find articles on such things, but it's unlikely
your setup has the same stimulus (too much heat behind screen).

https://discussions.apple.com/thread...art=0&tstart=0

*******

Video cards don't tend to make splotches. There was one video
card problem (driver related), where a discolored circle appeared
around some gaming elements. That's about as close to a splotch
as I could get. Otherwise, memory faults on a video card could
give colored rectangles (memory array that no longer writes
but reads back random garbage). I don't think I've ever heard of
a good "snow" type failure, except for people using too long
an HDMI cable. That makes colored snow. But with a short HDMI
cable, you're unlikely to have a video card make snow on
its own, or splotches for that matter. Some geometries
are harder to make than others.

Whereas a physical problem with an LCD monitor, can be related
to its physical structure. You can have vivid vertical lines
on an LCD screen, when the array driver ICs pack up. The array
driver failures seem to have a preferred direction for defects.
And on an LCD monitor with multisync scaler, the memory chip
on the scaler can fail - and you'd expect element geometries
similar to a video card defect. The difference is, the
video card can "amplify" a defect, whereas the scaler memory
failure, the faults stay "closer to the initial failure bit".

And the thing about the video card, is if something really
fails (shader program goes crazy), the video card driver
is likely to report "VPU recover" or "driver recovery in
progress" or similar. So a video card defect can't have too
much of an impact on card operation, or you'll be able to
tell from "screen blinking to black" that the driver
the OS uses is not happy with what the card is doing.

Paul