okay guys i already own a 4870x2, other specs are an msi 790fx gd70 mobo (4 pci x lanes) and an 955BE oc to 3.5 for everyday use (3.8 for benchmarks). firstly i cannot afford a 5870 at the minute so thats out the window, i know i've already got a fairly powerful system but i'm kinda greedy and wanna add more power to it and i've heard tri crossfire scales better than 4x crossfire. for the current price 4870's are going for would i be stupid not too add one and not need to upgrade again until dx11 really takes off.