The official GT300/Fermi Thread

[Cybercat]

The biggest difference between ATI and NVIDIA, the way I see it at least, is that ATI is basing his cards on "logic" sp's, which means that if you are able to make and awesome driver, you get and awesome performance, but if you don't...well, you stick with your reals sp's (160 in RV770, 5 ways each so theorically this makes 800sp's). On the other hand, NVIDIA is not that reliant on drivers as their arquitecture is more "beasty": no logical sp's means that you can improve a few algorythms but that's all...

So, ATI has a long way in order to make the RV870 as efficient as RV770. The only way we are seeing that poor scaling is because of that, they have to improve how the sp's work (in order to keep all of them feeded) and how to manage the new AF which is awesome but is showing as a HUGE problem (compared to older gpus in which AF has been nearly free).

That could also explain why there isn't more difference between 5870 and 5850: the more SP's you have, the more you have to work on a driver so we could say that 5870 is gonna get a lot better than 5850 will (and 5850 is already and awesome product nontheless). Within 6 months time I expect 5870 to totally kill 4870X2 performance wise in ALL games/benchmarks.

I agree completely. Just as you said, it's probably a lot harder for ATI to keep newer parts fed the wider their SP engine gets. I actually think their utilization goes down significantly as the SPs go up, resulting in poorer efficiency with each subsequent generation. It's why a GTX 295 with 1.8 TFLOPs is able to beat a 5870 with 2.7 TFLOPs. The amount of FLOPs matters even less than it used to, because it's all in how you use them.

A GF100 might have 1.7 TFLOPs when it gets released, which is only about 60% more than a GTX 285 at 1 TFLOP (more if you're rounding, of course). However, 1/3 of the theoretical FLOP rate in G80-architecture-based cards goes almost entirely unused in real-world situations. The FLOP rate on GF100 is what it can achieve in real-world, and on top of that, it's more efficient than G80/GT200's baseline FLOP rate.

AMD definitely has a ways to go with their drivers, as with a VLIW architecture they rely heavily on their compiler. Has anyone done any testing of AF performance specifically?