Custom Resolution Utility (CRU)

[jobby]

(02-13-2014 09:44 PM)ToastyX Wrote:  I've seen snow like that with certain monitors when the monitor can't handle the refresh rate or the timing parameters. Have you tried the "LCD reduced" timing option? It's meant to help in cases like this. Even if 75 Hz doesn't work, sometimes 76-77 Hz will work.

The settings on the left are just the standard timing parameters for 1920x1080 @ 60 Hz. With one particular monitor, I found setting the vertical total to 1100 allowed it to work at 83 Hz with DisplayPort.

The timing parameters don't affect the image with LCD monitors, but they can affect positioning with CRT monitors. Just use whatever works. The only issue is AMD video cards won't reduce the memory clock when idle if the vertical total is below standard, but I don't know if that applies to older cards with GDDR3 memory. Horizontal values usually work with multiples of 8, so you don't need to test every possibility.

Alrighty, thanks.
The snow can be fixed by using the default 'manual' timings at 73Hz, so that's fine. So far I've had no problems with those settings.

I thought the "out of range" message on a monitor is kind of a 'hard' limit, so I didn't experiment too much. But I did try "LCD reduced" now and I was able to squeeze another Hz (to 74Hz, any higher values didn't work). Don't think it was stable, though (once when falling back from a higher Hz the monitor remained stuck).
"LCD reduced" was also causing the video memory clock to be maxed out in idle, because of that vertical total being too low, as you said.
(BTW, using a Radeon 7850.)