When you say "static screen" are you talking about having the whole screen go to random-colored pixels? And by "flickering" is the whole image dropping out to white, or is it the "static screen" that appears really quickly?
I have a thin horizontal bar that will pop up randomly, and it is comprised of randomly colored pixels. When the signal is completely screwed up, I'll get a black screen, then the display will pick up the signal briefly for about half a second, then it goes to full static for about a tenth of second before going back to black and repeating the process.
I have a VegaFE, not an RX480, but if the problems are very similar, it is possible that this is a driver issue.
I got the same Problem, and i cant fix it but i seem some patron that may helpyou
1a.- The cable HDMI, sometimes its one cheap cable and as soon it get hot it fail, you can try changing a better cable
1b.- Change between Mode 1.0 (4k 24Hz) and 2.0 (4k 60Hz) on the TV HDMI Mode Option sometimes a fast change between those or a timed one will fix, Its some like a cold start fail, i sometimes conect to the computer via VNC, Teamviewer or similar go to Screen config, Adaptator propieties, and change from 60HZ to 24, Wait the 15 secnds to automatic restore to 60 and the problem goes away, Also when i start the monitor and says NO SIGNAL, i conect remotelly and change from 60 to 24 and get back to 60 (depends on monitor if you can do it fast or wait on every change to work, it could be tricky not allwais keep 60hz on first try, and some times i got a complete CPU freeze)
1c.- The memory on the card becomes hot, and do some funy stuff like glitches pops, out of sync ETC, you can try to speed up your fans or try to get cooler the VGA, specially Mems
Those solutions are independient one of each other, but together may fix almost all your glitch problems, including the one of NO SIGNAL