Kind of watermark on background video Philips monitor

[MrNice]

Hi,

My config is:
HW:
MB: Asrock
CPU AMD FX
Video: Nvidia GeForce GT 520
SW:
Linux version 4.3.5-300.fc23.x86_64
(mockbuild at bkernel02.phx2.fedoraproject.org) (gcc version 5.3.1 20151207
(Red Hat 5.3.1-2) (GCC) ) #1 SMP Mon Feb 1 03:18:41 UTC 2016
Xorg -version
/usr/libexec/Xorg.wrap: Only console users are allowed to run the X server
insmod --version
kmod version 22
+XZ +ZLIB -EXPERIMENTAL

Fedora 23

So far I had 2 Dell monitors E198 1280x1024, working fine side by side.
I had the opportunity to upgrade with 1 Monitor Philips 220W 1680x1050.
With Monitor Preferences I added it on the left side, primary.
Now on the Philips monitor, when I have a clear/white opened window or
background I see a kind of watermark, light brown, like a marble stone,
all stripes oriented down-left to up-right. One can find this type of
printing on some paper letter.

I created a full white picture and when I have this picture half on the
Philips, half on the Dell, the "watermark" is only on the Philips.
When I change the desktop background, it appears only on the Philips
monitor.
At first I thought this was due to an electronic interference, I changed
the cable from VGA to DVI. Nothing better.
There is nothing in the Philips monitor menu that could do that.

Philips monitor has 2 inputs: 1 DVI, 1 VGA
Graphic card, GF119 GeForce GT520 has 2 outputs, DVI and VGA for each.
I connected 2 cables, DVI and VGA on the Philips and changed the input
display with the monitor menu.
For the both inputs the issue is present, even with different resolutions.

So, I'd guess this is a driver issue, but this is a guess...
To confirm I could change to the Nvidia proprietary driver, but few
years ago I tried that with a very bad experience, so I prefer avoid that.

I don't know what this is and didn't find any similar issue in Internet.
Any idea what it could be and how to fix?


Many thanks