As you may know, some Radeon HD 6850 have been sent to the press with 1120 scalar processors instead of 960. KitGuru has published a comparative article between HD 6850 with 960 shaders processors and HD 6850 with 1120 shaders processors.
A radeon HD 6850 with 1120 shader processors
1120 shader processors means 160 scalar processors in more or an increase of shader computing power of 16%.
ShaderToyMark is a pure and really intensive pixel shader test. Most of shaders used in ShaderToyMark are math shaders (few or not texture fecthes at all). ShaderToyMark is nearly a GPU computing application!
And guess what? There is exactly an increase of 16% between both versions of the HD 6850 (see the chart above).
ShaderToyMark: HD 6850 with 960 shaders score
ShaderToyMark: HD 6850 with 1120 shaders score
In TessMark 0.2.2 (OpenGL 4 tessellation benchmark), it’s another story. In normal tessellation mode (which correspond to a tessellation amplifation factor of X16) the difference is around 14% which sounds normal. But in moderate tessellation (factor X8), the difference jumps to 36%. Don’t ask me why, I currently have no HD 6800 series in hands so I can’t test TessMark to see how it behaves with HD 6850 / HD 6870.
From TessMark comp. table, here are the score of some Radeon HD 5000 series in moderate tessellation:
– Radeon HD 5770 (MSI R5770 Hawk, 800 shaders, gpu core:875MHz): 20366 points
– Radeon HD 5870 (1600 shaders): 27000 points
I just received from Zardon, the guy behind KitGuru, the TessMark scores for a Radeon HD 6870 (1120 shaders, gpu core: 900MHz):
– Moderate tessellation: 23199 points
– Normal tessellation: 8342 points
The HD 6850 has a GPU core clock of 775MHz. Let do some linear math for the moderate tess level:
- a Radeon HD 6850 1120 shaders with a core clock of 875MHz would have a score of around 21100 points: the score is a bit above the MSI R5770
- a Radeon HD 6850 1120 shaders with a core clock of 900MHz would have a score of around 21700 points: the score is not too far from the HD 6870
In normal tess level, MSI R5770 Hawk gets a score of 7515 points, whereas the HD 6870 scores 8342 points.
- a Radeon HD 6850 1120 shaders with a core clock of 875MHz would have a score of around 7990 points: the score is a bit above the MSI R5770
- a Radeon HD 6850 1120 shaders with a core clock of 900MHz would have a score of around 8220 points: the score is not too far from the HD 6870
At first sight, the scores of the Radeon HD 6850 with 1120 shaders look normal. Actually, seems there’s a problem in the TessMark score of the 6850 HD with 960 shaders. This score should be higher like around 16000 points in moderate tessellation. But I stop here because I don’t have a HD 6850 nor HD 6870. Maybe there’s a bug in TessMark, or in the OpenGL driver of Catalyst 10.10 or in the measure… If someone has a clue, the comment section is there for you!