White noise on the monitor screen.

Sometimes, when my display comes back on, instead of a picture I'm getting just black and white dots but they are static and not moving like on tv screen. When I restart my comp all is ok. Until the next time...
My GPU are both new so changing them won't be a problem but what could be the cause? GPU or monitor?

Could be either, but I've seen faulty GPUs do things like that. Could you try plugging another source into the monitor and see how it behaves? Check cables, too

Will try. Thanks Ripper.