Need help upgrading my pc. Kinda stumped! AMD!

[bobbybamf12]

You may not even need to know this all of this but first forum post ever! so i'm going to try to do it right.
This is my first build don't hate!
MoBo: Asrock a770DE+
Cpu: amd athlon ii 3.3ghz 455 ( successfully unlock to b55 quad core)
Ram: adata ddr2 2x4gb 800mhz
Gpu: saphire hd 6670 ddr3
psu: 700w Apevia psu( Its not certified it say %80 if or if not that is true. I'm not going to need that much power anyways. 4 out of 5 eggs on new egg here the full model name. APEVIA ATX-CB700W 700W ATX12V / EPS12V SLI Ready CrossFire Ready Power Supply - OEM)
resolution: 720p ( upgrading really soon to a 900p buying from a friend for 30 dollars.)

Here what I'm planning on upgrading for the cpu to.
phenom ii 960t x4( Hoping it will unlock to 6 core like my athlon ii upgraded to 4 successfully also over clock it a bit.
or
phenom ii 980 BE( won't over clock it no need to really)

also i need a better cooler but I'm trying to find a decent one that can use the stock bracket don't really want to take my motherboard out of my pc.

gpu is going to be the first thing i upgrade.
I want the hd 7850 but i know its overkill and it might take awhile for the money but besides that.
I'm looking at a hd 6870 but I can't make up my mind between that or a hd 7770. So i figure i can get other people opinions on what would be good for 900p. I'm aiming towards being able to play bf3 multiplayer on ultra at 900p. Is a hd 6870 over kill or will a hd 6850 be good enough?

My max budget is $180.

[TherealYeno]

I would go for the 6870. As long as you aren't bottlenecking more GPU power is better.

[SauceBoss]

6870, it offers better performance then the 7770 and ita around the same price.
as for the cooler, get the the hyper 212 EVO. its the best bang for the buck in the after market coolers.
also if the Scyte Katana 3 is sold at your country i would prefer it.