If there are different versions of a card then what you have to look at is the core clock speed and naturaly the one with the higher clock speed is going to give the higher performance. If you are talking about the different manufacturers like XFX , Saphire , Asus , Gigabyte and so on , they all have to use the same gpu from AMD and then they put it on thier PCB but they follow the reference design from AMD for putting the card together and they can put different amounts of memory and they can set the core clock as well so that the card comes preclocked from the factory.
So you can easily tell what card is going to do what by looking at the core clock and the memory , the higher the clock the better the perfomance. If I had two cards in front of me one a Saphire 6950 at 825mhz and the other an Asus 6950 at 900mhz I would go with the Asus card because I would expect better performance from it. If they were both clocked the same then I would try to see if there was something else that would seperate the two , maybe the amount of ram or a better cooling solution.
From what each company normally does with their special versions.....I usually look at Asus and MSI.....and I'd be buying a factory overclocked model as they usually come with upgraded coolers and more robust VRMs. Here's a summary of the 6950 and 560 Ti in both reference and factory OC'd models
Guru3D uses the following games in their test suite, COD-MW, Bad Company 2, Dirt 2, Far Cry 2, Metro 2033, Dawn of Discovery, Crysis Warhead. Total fps (summing fps in each game @ 1920 x 1200) for the various options in parenthesis (single card / SL or CF) are tabulated below along with their cost in dollars per frame single card - CF or SLI:
Thank you everyone for all of your helpful information!
Typically I'm all down with Nvidia cards, but earlier this year, I picked up an ASUS Formula mobo with ATI chipset, and 1090T CPU (being a die-hard-AMD-for-gamers fan) as I was trying to future proof as much as possible. After BF3 came out, I recognized the need to upgrade my 9800gtx GPU (low settings) and decided on the 6950 series as it's somewhat newer (than mine) and that I could crossfire it later on down the road with my mobo. I'd like to be able to play the game without any jagginess and lagginess on higher settings than low.
My mobo is a Crossfire Formula IV with an AMD 1090T CPU. Does anyone know if the MSI HD 6950 TWIN FROZER 2GB would play nicely together with my mobo and still run BF3 on ultimate settings? Would the 1 GB be better as I've read somewhere that the GPU would run out of juice before all of the memory would be utilized on the 1 GB?