My RX 480 has the lights flashing a dull green and it does not display any picture
That doesnt sound right.
I know any ideas
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check your PSU & cables maybe either of these quick simple fixs first. Try the simple things go around & do the simple steps before doing anything. Got a spare HDMI cable & PSU try them first & eliminate any problems like that first before thinking your cards died. Had a PSU die a while ago by Videocard getting a bit of power thinking the mobo died threw in a working PSU & fired up first pop so try these ideas first. Been here done that.