[CentOS] Strange dots on monitor

I forgot to write that the dots start to appear only inside "Desktop
Environment" (in my case Gnome), not for example in grub/bios. Today I
tried to install ubuntu 16.04 and the green dots appeared there too (in
Unity).

On Sun, Dec 17, 2017 at 12:50 AM, vychytraly . <vychytraly at gmail.com> wrote:

> Hello friends,
>
> about 2 days ago, unexpected strange green dots started to appear on
> monitor of my laptop running centos 7.4 with nvidia card. I enclose photo
> of the problem. Before it was running perfectly fine, I did not do any
> updates of the system / drivers last few weeks, so I am not sure what can
> it be related to. When I try to do screenshot. The screenshot captures
> screen without the dots. But now comes the strange thing: when i am in the
> running system already and i do "systemctl restart gdm", X restarts and the
> green dots disappear, everything looks perfect after that.
>
> Please could you give me some advice how can I resolve this problem? I
> suspect that X could have some problems to properly "indetify" the monitor
> and therefore it creates this artifacts? Or do you think it could be
> hardware bug of gpu/monitor?
>
> Thank you very much for any advice
> Have a nice day
>
> Vych
>