The problem is; you went with an AMD for this.
You should have consulted us a bit before you bought all the parts.
(Unless you did, AMD is fine to go with if you are on a budget)
The 3570k Can run circles around anything AMD thrown at it.
other than a couple of the 8XXX series processors, those only outrun the 3570k in extreme rendering.
That FX is probably bottlenecking in BF3. A core i3 is faster than a 6100 unfortunately, unless you do an insane overclock on that processor it will bottleneck in BF3. It says right here that a FX-6100 is about equivalent to a Q6600 from 2007 from Intel. http://www.tomshardware.com/reviews/gaming-cpu-review-o...
Depends on his resolution or how many people are in the game. Yeah it might say it can run on ultra but when it comes down to it the FX processors lag when 64 people are playing on the same server. That or it could be a power supply issue, overheating issue, or driver issue that is causing the slowdowns.
I get 50+ fps with all high with some ultra settings and no AA deferred on Battlefield 3 and Medal of Honor with a Phenom II X4 970 BE and a Radeon HD 6870 1GB....It is not your CPU, the hardware reviewers at TOm's Hardware found that BF runs fine on Ultra on a Phenom II dual core (I have quad) with 70% load on Ultra.
i do slightly regret not putting out more to go the intel direction but my budget was already streched and i did rush a bit. however i did make sure to read as much as i could before hand, and it seemed generally that there is plenty of people running with much better results on the same AMD and people that can hit 60 fps on a 7870 in ultra.
either way, drivers are all fully updated. and yeah all the settings maxed out on ultra im getting max (rare) 30fps, but if i take everything down to the lowest settings im reaching 70 maybe 80 fps. this is on 1360 - 768 res. that seems just bad to me. i was playing last night for a few hours generally on high setting no msaa aa or anything on and i was getting a steady 40 - 45 fps ???
as i have just come for playing on the 360 i aint complaing so much about the quality of my gaming, cause its a lot better, i just struggled to put money for this and it aint getting me the results i expected at all, seen laptop benchmarks of a similar price coming pretty close....
He said settings in the game change FPS, so it has nothing to do with CPU, people. It is probably a GPU issue. Try newest drivers, make sure all power is connected, etc. Call tech support for the video card issues.
You may have settings in the catalyst control center that are hurting your performance....like extra features enabled, at least that is what I have been told in regards to a problem with an old nVidia card I used to run....