This sounds like the same bug I reported a few weeks ago here:
It used to work perfectly until I updated the driver from the 185.18.xx to 190.42. Unfortunately I can't switch back to the older driver because I updated to xorg-server-1.7, and the nvidia drivers didn't support the new xorg-server until 190.xx.
I think it has something to do with the cards not being reinitialized correctly upon resume, because if I kill the flickering xserver by hitting ctrl-alt-backspace, it restarts and works without the flicker.
You should run nvidia-bug-report.sh and post the result file here for the nvidia developers to look at.