Take the RX 550 out,use the integrated gpu and use DDU to get rid of the AMD drivers. Then put the RX 550 in again and see if you will get an image.
Also what psu exactly?
the psu is a "EVGA 400 N1, 400W"
i should also note that the pc only crashes when i was loading up a game or browsing intense web pages also i re-formatted the pc before installing the gpu, could it still be a case of bad drivers?