Radeon 6850 vs 6950?

Vid krävande applikationer (bf3, ac3, m.m) kommer du att märka skillnad, men det blir ingen stor skillnad.

http://www.hwcompare.com/6218/radeon-hd-6850-vs-radeon-hd-695...

Radeon HD 6850 vs Radeon HD 6950 2GB

Intro

The Radeon HD 6850 has a GPU clock speed of 775 MHz, and the 1024 MB of GDDR5 RAM is set to run at 1000 MHz through a 256-bit bus. It also is made up of 960 SPUs, 48 Texture Address Units, and 32 Raster Operation Units.
Compare those specs to the Radeon HD 6950 2GB, which comes with a clock frequency of 800 MHz and a GDDR5 memory speed of 1250 MHz. It also uses a 256-bit bus, and makes use of a 40 nm design. It is made up of 1408 SPUs, 88 Texture Address Units, and 32 Raster Operation Units.

(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6850 127 Watts
Radeon HD 6950 2GB 200 Watts
Difference: 73 Watts (57%)
Memory Bandwidth

As far as performance goes, the Radeon HD 6950 2GB should in theory be quite a bit superior to the Radeon HD 6850 overall. (explain)

Radeon HD 6950 2GB 160000 MB/sec
Radeon HD 6850 128000 MB/sec
Difference: 32000 (25%)
Texel Rate

The Radeon HD 6950 2GB will be much (approximately 89%) more effective at AF than the Radeon HD 6850. (explain)
Radeon HD 6950 2GB 70400 Mtexels/sec
Radeon HD 6850 37200 Mtexels/sec
Difference: 33200 (89%)
Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 6950 2GB is the winner, but not by far. (explain)
Radeon HD 6950 2GB 25600 Mpixels/sec
Radeon HD 6850 24800 Mpixels/sec
Difference: 800 (3%)

Please note that the above 'benchmarks' are all just theoretical - the results were calculated based on the card's specifications, and real-world performance may (and probably will) vary at least a bit.

Här har du en direkt jämförelse mellan ett 6850 och ett 6950:
http://www.anandtech.com/bench/Product/539?vs=510

Så det är ju en ökning, men som sagt rör det sig inte om en stor ökning.
Det handlar helt enkelt om hur mycket du betalar för att byta upp dig - efter en viss summa pengar är det bättre att helt enkelt köpa något starkare, så att man faktiskt märker en skillnad.