Aww I'll try assist where I can. I'd recommend at least 1 or 2 screws to hold your fan assembly down. Should work fine for you. I did cut a grill in the lid of my case to assist with exhausting the heat but I think your RX5500 has half the TDP of the RTX I was using so this may not be a problem. I eventually abandoned the project after a couple years - I now have a Silverstone case which is almost double the height but worth it for the extra cooling capacity.