Root window shimmers with new nVidia graphic card

[Harold L Hunt II]

GChampoux@williams-int.com wrote:
> I just got a replacement PC:
> HP xw4100 with nVidia Quadro4 980XGL graphic card.
> The previously PC was a Compaq DeskPro300 with an nVidia Quadro2 MXR.
> 
> I re-installed cygwin as usual, and it operates properly.
> However, I've noticed something unusual in the display of the root
> window and scroll bars.
> They both "shimmer" as if the refresh rate was bad.
> Changing the refresh rate had no affect.
> All other windows (CygWin X or MS Windows) and their contents are fine.
> If I use multi-window (integrated window manager - no root window) the
> scroll bars still shimmer/vibrate.
> If I use xdmcp, the problem is not present at all.
> 
> It's only a nuisance, but I would like to address it.
> Maybe a driver setting?
> I'm using 52.16.
> 
> CygWin version is 1.5.5.1.
> However, I did try the latest (1.5.9.1).
> Problem is unchanged.
> 
> Any recommendations?

Yup, it has nothing to do with Cygwin/X.

I wish you would have told us more about your monitor.  Is it an LCD 
panel connected via a VGA (standard video for computers) cable, or is it 
something else?  This problem occurs in the circuitry or cabling when 
you use certain combinations of video cards and monitors over VGA 
cables.  For example, I have five old video cards and a 19" 1280x1024 
LCD panel; if I run it with four of the five video cards over VGA cables 
I get the shimmering you speak of, while the fifth video card does not 
cause the problem.  Oddly enough, the one that does not cause the 
problem is one of my oldest video cards.

You will almost always be able to notice a very small amount of that 
shimmering affect with any video card over VGA cables, but you'll have 
to look very closely to be able to see it sometimes.  This problem 
doesn't usually occur when using CRT monitors and I believe this is 
because the shimmering is caused by a combination of the video card, VGA 
cable, and the circuitry in the LCD panel that changes the analog VGA 
signal back to a digital signal to drive the LCD; this conversion is a 
lossy sort of process and it would make sense that small variations in 
the incoming signal could get amplified during the conversion process 
thus causing the shimmering.

So, if you have an LCD panel and you've got it hooked up with VGA 
cables, then hope and pray that your LCD panel also has a DVI (digital 
video interface, or whatever they have renamed it these days) connector. 
  If it does, you're in luck though you may have to get a new video card 
if your current one does not have a DVI output; if it doesn't, get used 
to the shimmering or steal one of your co-workers hardware :)

Good luck,

Harold