What's the issue/fix with Geforce FX and DX9?

[Hauk]

I've only read bits and pieces. What's the issue with Nvidia and DX9 exactly? Is it the poor benchmarks reported from Half-Life 2?

Also, what's the fix? The FX5900 series for example, can a fix be achieved with better drivers, or am I wishing I should have finally gone ATI??

 

[VIAN]

From what I gather. Nvidia's FX line has a performance problem with shaders, which is the heart of DX9. Supposedly, Nvidia coded their hardware based on their Cg compiler, while DX9 games are coded with HLSL compiler. This is why Nvidia has been doing so badly. I guess they feel cheated by what Microsoft did by releasing HLSL, and thats why they started to cheat.

 

[Genx87]

I dont know if it was because of thier CG compiler or Microsoft dinking around with the precision.

I have done a little research and up and until around July 12th of 2002 it appears FP16 was going to be the precision needed. Sometime between then and when they changed the precision to an odd 24FP Microsoft and Nvidia must of had something go foul in their relationship. If one was a conpspiracy theorist you could see that I believe Nvidia and Microsoft started a lawsuit about xBox chips.

Hmmm...................................

 

[Jeff7181]

The way I understand it, a long time ago nVidia saw the need for an advanced language. They told Microsoft... Microsoft decided it wasn't necessary yet... so nVidia started work on Cg and the GeForce FX GPU. Then when ATI went stated they felt their was a need for an advanced language as well, Microsoft went ahead with DirectX 9. So by this time, nVidia had created Cg, and the GeForce FX was half way through development... they couldn't just scrap the whole GPU... so they did what they could to support DirectX 9. Obviously since the GPU was designed for their own language, it doesn't work as well with DirectX 9... it's like trying to run a Mac OS on a PC. It may be possible with some modification, but it will never be as fast as on Mac hardware because the OS was designed around the hardware.
Again, the way I understand it... these new drivers sort of "translate" DX9 instructions into something the GeForce FX GPU can handle easier. And now there's rumors of Microsoft working more closely with nVidia with DirectX 9.1 to correct the performance problems, or at least make them less noticeable.

 

[Blastman]

My thinking is that Nvidia spent so much real estate implementing 32 bit (the NV35 ~133M transistors is already quite a bit larger than the R350 ~ 110M) they had to cut back in certain areas, which meant implementing less shader units = lousy DX9 performance.

 

[Jeff7181]

Originally posted by: Blastman
My thinking is that Nvidia spent so much real estate implementing 32 bit (the NV35 ~133M transistors is already quite a bit larger than the R350 ~ 110M) they had to cut back it certain areas, which meant implementing less shader units = lousy DX9 performance.

That might be true... nVidia's origional design, using the Cg compiler, would not have included these DX9 shader units, because DX9 shaders were non-existant when they started creating the GF FX GPU. You could say it's similar to Ford's engineers building a car that they intend to be a front wheel drive compact with an inline 4 cylinder engine... then someone says "nah, lets make it rear wheel drive with a V8" when they have a prototype built.

 

[JasonandBecky]

Once DX9.1 comes out things might change a lot yet again.

 

[BFG10K]

The NV3x line will always have problems running shaders. It has extremely limited temporary registers and you have to heavily optimise around this in order to get anything resembling decent performance.

ATI's R3xx line beats it in both brute force and IPC and it'll take staright shader code and give you excellent performance.