6850 or 6870?

I know that adding a 3rd card to a 6870 crossfire eliminates the instabiliy but all i've heard is on a 6870 crossfire and nothing with a 6870/6850 crossfire.I haven't heard of any 6850 crossfire problems so I'm wondering is this soley just a 6870 problem?

I honestly didn't know you could xfire a 6850 with a 6870  ... but I would give it a try

You can always return it  

But returning it to Newegg costs's a restocking fee.

really? ive returned atleast 3 items, never any fees at all D:

You never paid a restocking fee?

1- What problems do you mean ? HD 68xx series in CF are known for loving Microstuttering, CFing HD 6870 with HD 6850 will get it worse IMO (due to the synchronization of the different GPUs, unless you OC the slower card), besides you'll waste some of the HD 6870 performance when CFing with HD 6850.
2- I guess you know what is the Microstuttering, so far i did some google search and found out that VSync can help to prevent "microstutter" by enforcing a fixed regular frame update rate, no matter how quickly the next frame is or isn't ready the framerate will always be at 60.
3- I asked a member here called "megamanx00" or someone else i don't remember really, he had a HD 5870s in CF with a 955 BE, i asked him if he gets a bottleneck with this configurations and he said yes but that means he is not able to get the maximum FPS he should get with the HD 5870s in CF with the 955 BE compared to i7 2500K with the same GPUs. So you might want to OC your CPU harder or better wait for a strong CPU.

What I've seen from the benchmarks is that a 6870 crossfire is just "unstable".When adding a 3rd 6870 to the crossfire it seems to eliminate this which is why I'm thinking it's just happens to be a 6870 problem.I haven't heard of anything on a 6850 crossfire causing problems which is what also leads me to believe again that this is just solely a 6870 problomatic error.

My main focus here is on BF3 and that it is mainly a GPU limited game(number of cores or freq doesn't really play a factor).That is why I want a 6870 crossfire.

Did you read the "Microstuttering" article by Tomshardware ? The issue like never existed with 3-way CF/SLI and barely noticeable with High end GPUs such as Hd 6950s and GTX 560TIs and "above"in CF/SLI.
From your post i understand that you're going only 2-way CF, BF3 currently have problems (crashing and lines) with both CF/SLI configuration, i completed the game @ 41-58 FPS with my HD 6950 OCed @ 920/1400. I never had a problem, not sure if EA has released a patch or there's a fix for the BF3 problems with CF/SLI.
Be advised that not every game is a GPU intensive only, MW3 has disappointed me, i get a constant of 43 FPS no matter what i do, i lower settings, resolution & bla bla bla... i'm limited by the CPU even @ 4.0 GHz. it sounds like Skyrim as well a very CPU intensive, i downloaded and gonna try it now, give a look below, no matter what GPU you do have, the CPU is gonna hold you back, unless you have a monster like the i5-2500K.

I stated in my previous post I'm only concerned about BF3.I know the differences of CPU's from the benchmakrs and BF3 is really a very GPU limited gamed so long as you have at least a quad core.\

That's true, but are you going to have the the Multi GPUs only for BF3 ? Anyway if you're not concerned about microstuttering i would recommend 2 HD 6870s in CF for the maximum performance.

My own personal advice is to wait for the new series, they might eliminate all those issues experienced in the HD 5K & 6K series by enhancing the drivers. Also, 1 high end GPU is better than CFing 2 low end/mid-range GPUs.

I am concerned about microstuttering that's why I started this thread.lol.

The only game I play that I would truly utlize such gain is BF3.Yes I know but,as always, I already own a 6870 which is why I would want to crossfire.My whole basis of starting this thread was to rule out if it is just a 6870 problem or if it continues down to the 6850's as well."Technically" if I crossfire my 6870 with a 6850 it would be a 6850 crossfire(based on clock speed) with slightly more shaders.

It's better to use two 6870s rather than a 6870 and a 6850. If one card is significantly faster than the other the stutter is more noticeable when it occurs, at least to me. Since BF3 seems to have trouble with CF and SLI (I haven't played it yet myself) I say you hold off on that and perhaps just OC your card to help smooth things out for now.

@megamanx00
i just mentioned your name above xD
That's what i said too, since the synchronization is not the same the microstutter would be worse.

@ OP
As i told you, and you can search the forum for similar threads, everyone was going for HD 6800 in CF i have said No because of microstuttering, even tom's article example was based on a pair of HD 6800 in CF. It's with every multi GPU setup in CF/SLI but barely noticeable with high end GPUs.

I don't see the game unplayable if you get a 35-40 FPS, but i believed it runs smoother with higher FPS and i noticed that in Crysis 2 DX9 mode.
What do you mean by "slightly more shaders" ? As in CF/SLI nothing is shared or combined between the GPUs except for the "Workload" so the CF might goes to the lowest shaders GPU, i'm not sure about this, someone correct me if i'm wrong.

Purple, your MOBO doesn't even support crossfire.

If you crossfire a 6870 with a 6850 won't the 6870 be downlocked to meet the 6850 speeds but the 6870 shaders will remain the same?

Alright well I have another question.I realize that this PSU will be stretched to it's limits but do you think t's possible to run a 6870 crossfire on a Seasonic 520 wattt PSU? It's rated for 480 watts on the +12/v rail and what I've been seeing on the power consumption benchmarks is roughly below 450 watts.What do you guys think?

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Yes I know that.I will be upgrading it when/if I get the other 6870.

421W for both GPUs in CF, not the entire PC
http://www.guru3d.com/article/radeon-hd-6850-6870-cross...
600W is recommended for your system, 700W for OCing both cards and CPU.

No no.It's the 6870 crossfire and the rest of the PC.
BUT I always assume that benchmarkers use a test bench therefore no case fans,etc.

System Wattage with GPU in FULL Stress = 421W

Subjective obtained GPU power consumption = ~ 275 Watts

Skyrim sounds to be good with my setup, a constant of 60 FPS drops occasionally to 50s.

From guru3d

It's a bit confusing, they say so and give the table with the power consumption and say the opposite above.

So you're fine with the 520W PSU if you won't do a serious OCing. Better get a 600W PSU.