With DX9.0c 32-bit precision, are the x800s going to be disadvantaged?

[webmal]

This time, the x800s are sticking with the 24-bit precision while DX9.0c will be 32-bit. I believe the x800s will incur a performance overhead when converting their image quality up to the DX9.0c standard in applications using Microsoft's API. This is going to be similar to the GeForce FX series not adhering to the DX9 path (32-bit precision instead of 24-bit).

XP SP2 (due in the next few weeks) includes DX9.0c.


1. Will the x800s be disadvantaged?

2. Will my 5900XT's performance improve?


Webmal


Edit: Inserted the word "precision" - thanks vshah!

 

[vshah]

the 24 bit and 32 bit are not color modes, there are math precisions. both cards will operate just fine in 32bit color.

however, as x800 cards don't support 32bit precision, they don't fully support dx9.0c. nvidia does.

you're thinking of two seperate things here...

 

[Pete]

Correction: current ATI cards don't support full precision in PS3.0 (which was raised to FP32/128-bit from FP24/96-bit in PS2.0), but they can still run in "partial" precision at FP24. (ATi cards are FP32 in the vertex shader.) And all these cards don't upconvert to the "DX9.0c standard" (you mean "PS3.0 full precision"). When they output their data, it's to a lower-precision INT8/32-bit buffer (from FP16/24/32//64-/96-/128-bit shader data formats).

Nit pick: SM3.0 ups full precision to FP32, not DX9.0c.

AFAIK,

1. The X800s won't be disadvantaged per se as they're SM2.0 cards, so they won't be running anything in SM3.0 "mode."
2. Your 5900 is also just SM2.0, so, similarly, SM3.0 won't affect it.

 

[BFG10K]

I believe the x800s will incur a performance overhead when converting their image quality up to the DX9.0c standard in applications using Microsoft's API.

No they won't, given they'll do no such thing.

This is going to be similar to the GeForce FX series not adhering to the DX9 path (32-bit precision instead of 24-bit).

Huh?

1. Will the x800s be disadvantaged?

There is no evidence to suggest FP24 causes visible IQ degradation over FP32 so no, I don't think they will.

2. Will my 5900XT's performance improve?

Nope.