I was kinda worried that perhaps my mobo was incompatible for the hd4870 but i saw hd4350 is also pci-e express 2.0 .. is this true? Also will the psu work on my mobo? I've been asking around lately and i'd just love one or two more opinions. This is the first time i'm upgrading my desktop ( parents won't usually let me ) and i just like to know for sure. I'm a gamer and i love great graphics but my hd4350 won't let me .. it's my cpu keeping me alive ^^ ( I game at low res )
Both the PSU and GPU should be fine. I'd wonder though, why the ATI 4870? There are newer cards out that are better & faster than that. Depending on the price, you could get a better card for the same money.
Regardless, the 4870 is going to be a big jump in performance compared to your 4350.