what's better for gaming the amd phenom II a8 x4 with a Asus F 1A 75 -V EVO mobo and radeon 6770 gpu against the amd phenom II x4 840 with a GIGABYTE GA -970 A -D 3 mobo and a radeon 6850 sorry I didn't put links I don't know how to on my phone
If I had to pick one of these I would pick the one with the 6850. But as stated that still wont bemaxing out crysis. If you have a little bit more money at all get a 6950.
What kind of games, what resolution and what detail are you looking for? Either of these will run games, but depending on the specs and what you want, it might be the right fit or not.
1080x1020 I want to play games like crysis and bf3 on high or Max settings . I'll have 8gb of ram.
I'm assuming you meant 1920x1080?
Neither of those set ups will be able to run at max, and maybe not even high settings. Take a look at the benchmarks for the 6850: http://www.anandtech.com/bench/Product/291
As you can see here, Crysis 2 requires a pretty strong GPU even for Gamer (lowest quality) settings.
If I had to pick one of these I would pick the one with the 6850. But as stated that still wont bemaxing out crysis. If you have a little bit more money at all get a 6950.