I just bought a Mac Pro 3.1 off eBay that was in very good condition for $200. it has dual Intel xeon 2.8ghz processors, 10 GB ram which I already plan to upgrade, 320 GB hard drive and the video card is a Raedon 2600 XT. its also running El Captain 10.11.5. I know nothing about video cards except that this one should probably be replaced or upgraded. I found a radeon HD7950 and a radeon HD 7970 on eBay, it says on both listings that they are intended for Mac. you can find the 7950 here: https://www.ebay.com/itm/192425916981 and the 7970 here:https://www.ebay.com/itm/192425916981 if you care to look. I am just wanting to know the better of the two. or is there a better option for cheaper? I bought this for a light gaming computer if that helps at all. P.S. I have found a pair of xeon 3.2ghz processors for $150. would I be able to notice a difference in performance if I upgrade the processors to the 3.2ghz? P.P.S.I know that both of the video cards cost more than I paid for the computer itself. I don't need it pointed out to me.