Im actually gonna be getting a 500W from a friend nowFor a P4 system with only 300W PSU, your choices are simple. Grab the cheapest card you can find. Chances are the P4 will be a bottleneck, and the 300W PSU limits you to under $80 anyway. My advice would be to look at AMD. Even though I am an nVidia guy, In my opinion nVidia doesn't have price/performance cards at that price point.
I seen a guy using a P4 and a Radeon 7970? playing BF4 on all ultra at 10-11fps you think I could play on med/high with a R7 250?I would probably suggest an R7 250. Thats about the best I would get on that system because no matter what that processor is going to heavily bottleneck any GPU you get in this day and age.
Honestly I just wanna play the S.T.A.L.K.E.R Series because I love games like that and also Fallout New vegasYeah and with the P4 being the bottleneck, you could probably get those results with an R7 250 on the same settings.
http://www.kitguru.net/components/graphic-cards/zardon/sapphire-r7-250-ultimate-review/16/
Well if you plan on playing BF4 you can't expect much. However if you want to stick with this machine, grab an R7 250 and you should get a noticeable improvement. Plus in BF4 you can enable Mantle which will make things smoother on that specific game with your P4.It was free to me so I cant complain
if I gotta put $80 in it