Recommended AMD Graphics Upgrade for his Computer

So with what money I got, I figure that since I didnt get much of anything for my dad for christmas, an upgrade to his graphics card as well as a new monitor would be a nice thing to do for him (he left his old one on and it has a bad case of screen burn, still works but retains image of desktop after a few hours, no LCD Conditioning mode on his monitor fixes it), a late christmas gift so to speak. he doesnt do heavy gaming, he primarily does light gaming, but mostly ancestry work, watches youtube, and other non-gaming stuff. wants to get into rust so he can play with my brother, but otherwise has little major games installed on his desktop

now I got my eyes on a basic monitor for him, nothing fancy like freesync or 4k stuff, just a basic 24" monitor with HDMI capability and maybe a displayport, nothing else, but what im puzzled on is what graphics card should I get him that would be a good step up from his old one; im not looking for a really expensive graphics card for him, just something that will outperform his old one, will fit into his computer with little to no spacing problems, and will hopefully work for a long while without any useless Video TDR Failure blue screens (that was a pain to fix btw, a true pain), pricing is also a thing (will primarily hunt for it on ebay, unless amazon or other vendors can offer a cheaper price)

attachment shows his stats via speccy, and will also provide a link to his userbench results

It's a sorry state when no proud AMD user replies .. (so disappointing!)

I'm a software person but from my experience .. the RX580 does the job.

checking out its specs on the amd website and userbenchmark, and so far, its a bit average, but for him, looks good

only problem I got, is his desktop is a dell XPS 8500, and unless im wrong, essentially has the same psu I got, a 450W stock PSU, so unless it'll still work with his computer, ill need a new PSU to put in his computer

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also I compared that graphics card to my GTX 960 and wtf, its better than my own? maybe I need to switch to amd or get a better gtx card then

If you use the media creation tool, it's a free upgrade to windows 10. He'll get better performance, keep all of his installed things/files and won't be at risk of running a OS that's near End of Life.

If you notice any power issues with the new hardware/os, look into replacing that psu btw.