Is this card worth crossfire? Or should I get a 5770 instead?
Will the results that I get be doubled?
e.g. i get 15~20fps in VERY HIGH DX11(40fps in dx10) metro 2033, so will i get 30~40fps?
Is it something like two cars go faster than one?
Two HD 5670 Crossfired can perform just as well or better than a single HD 5770, but it is not always the case. Crysis is an example where the HD 5770 will be faster. In most cases it will be worth it to install another HD 5670. Also, not all games will take advantage of Crossfire / SLI.
ya i would go 5770 i have a 5670 and 6870 but before i got the 6870 i tried 5770 and it blew my 5670 outta the universe. Im pretty sure it has to do with the external power the 5770 requires as to where the 5670 draws from the motherboard, cause ive heard even 4870's which require external power blow 5670's outta the water. Thats just my opinion and expierience with the 2 cards but im far from a computer wiz. Recommend xfx brand. And maby keep your 5670 cause im pretty sure you can crossfire the 2 cards
A second 5670 is a pretty cheap upgrade ($90 for another 1GB card) for you so I say go for it. Crossfire X works pretty well so unless you're playing any games where crossfire is especially problematic, like Force Unleashed, you will be happy with the improvement. You generally will probably get a 60-85% improvement depending on the game. If you want more than that though then it would be better to save up for at least a 6850.