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-   -   Benchmarking Doom3 Renderpaths... (http://www.nvnews.net/vbulletin/showthread.php?t=40192)

msxyz 11-07-04 09:07 AM

Benchmarking Doom3 Renderpaths...
Ok, this week I had some spare time on my side and I finally performed some experiments I had in mind for a while...

Since Doom3 supports multiple render paths, involving the use of different pixel shader instruction sets, I made some comparison between them. I was particulary interested in ARB2 vs NV20 path performance on NV3x hardware. I happened to have one spare NV34 (a XFX GeForce5500) so I could also benchmark my NV36 card against the "older generation" NV34 core. The results are interesting.

Test metodology: Detonator 65.73, Quality settings, no trilinear optimizations. Doom3: high quality, 1024x768, Anisotropic filtering disabled. I used a custom timedemo recorded from the intro scene (1785 frames). Tests repeated 5 times, I dropped the highest and lowest value and made the average from the remaining three...

I've also tested NV10 and ARB paths but I don't feel they're interesting to my research. Instead, I concentrated on the ARB2 vs NV20 path comparison because they are both usable on the NV3x hardware and they look quite similar.

Now, to the numbers...

GeForceFX5500 (270MHz core / 200 MHz DDR)

ARB2 path: 12.0 fps ; NV20 path: 14.0 Difference +16.6%
Shadows/Advanced SFX disabled:
ARB2 path: 18.7 fps ; NV20 path: 23.5 Difference +25.6%

My comment: On the NV34, the NV20 path is much faster than the ARB2 path, despite the fact that it requires multiple passes to render the frame. I was expecting such results, but the gap really impressed me. If any of you has a low-end 5200/5600 on your PC and wants to play Doom3, the NV20 path may be a better solution. The NV20 path does not support the "heat haze" effect and it has a slightly worse image quality but it may be a better compromise than reducing texture quality or disabling some features. PS: As you can see, a GeForceFX5500 is not the ideal card to play Doom 3 at 1024x768! :)

GeForceFX5700U (475MHz core / 450 MHz DDR)

ARB2 path: 25.2 fps ; NV20 path: 24.3 Difference -3.5%
Shadows/Advanced SFX disabled:
ARB2 path: 32.4 fps ; NV20 path: 29.9 Difference -7.7%

My Comment: on the NV36, it seems that switching from the ARB2 to the NV20 path will cause a little performance drop. NVidia did redesign the NV35/6 core to boost its performance with PS2.x shaders. Using the NV20 render path on a GeForce 5700/5900 affects both performance and quality in a negative way.

Well, these are my findings. I do not claim them to be 100% accurate. Both cards were probably held back by my slow CPU. I wish I had a FX5600 and a FX5800 to throw into the test. Maybe some of you can try and see if the results are similar

ChrisRay 11-11-04 05:14 PM

Re: Benchmarking Doom3 Renderpaths...
Nice and interesting information. I guess registry issues is what allows the NV2x path to be faster for Nv34 users. Good show.

msxyz 11-13-04 05:01 AM

Re: Benchmarking Doom3 Renderpaths...
Not only registry isssues but the fact that, when using ARB2 path, the NV30/1/4 hardware cannot use its FX12 ALUs to boost shader performance. It seems that the these additional ALUs may be used only with PS 1.1 or through NVidia properietary extensions.

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