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Old 10-25-04, 02:34 AM   #29
ChrisRay
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Join Date: Mar 2003
Location: Tulsa
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Default Re: why do fx cards perform so badly in 3dmark05

Quote:
Originally Posted by zakelwe
A technicality ? I didn't comment on the cart but your wording.

To quote you

"But geometry plays a huge role "

this is an exageration.

" But its just as much vertex limited as it is pixel limited."

no it isn't.

I didn't say anything about your chart being a 6800nu, I said assuming you had a 6800nu because that is the card most people will be trying to increase the pipes and vertex units on.

I keep seeing these comments about 3dmark05 being vertex limited and they seem to be coming from B3d it seems. If you look at the top scores for the 6800nu though you will see that a prereqisit is that the card is a 16 pipeline card. I have to say that if someone gave me a 24 pipeline card with only 6 vertex shaders I would not be too unhappy

Regards

Andy

Geometry does play a large role. Did you actually "look" at the chart? Comparing 2 vertex units to one quad, There is a substancial loss in performance. Sure one quad has a larger impact than 1 vertex unit, But 1 quad implements 4 dedicated shader units and 4 shared units, 1 vertex unit is exactly 1 vertex unit.,

In Some cases the vertex performance lost by 2 units is > than the loss of 1 quad, Therefore it shows 3dmark is also quite dependent upon geometry, Some tests, paticularly test 2 are unrealistically dependent upon it.

The reason that people are saying its geometry dependent too because it is. And it helps describe some disparity people are seeing with 3dmark in regards to pixel pipeline/vertex performance between ATI and Nvidia, Where the actual vertex performance is playing a large role.

I'm glad you like your quads, But it no way makes vertex performance any less important,.

And no, You said you assumed I was using a 6800NU, if you read the graph it clearly says I was using a GT with clock speeds illustrated.


Edit:

To reiterate, 1 quad "Should" have a larger impact on performance than 2/1 vertex units, Because it has 8 shader units per quad, But the fact is 2 vertex units are causing disparity between 1 quad, shows that the test relies on vertex data quite a bit.
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