Hello again,
your temps look absolutely fine.
I guess you could try looking into the cables as I mentioned earlier. Check if the cable connecting the monitor to your GPU is not loose. Also you could try using a different connection. If you are using HDMI cable you could try connecting the monitor via DVI or something.
I was about to suggest updating your drivers but it won't make much sense as you said that after restart the PC works fine. I'm starting to run out of ideas.