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Germans claim Nvidia caught "over optimising"

Flickering knickers in a twist
Tue Aug 30 2005, 16:38
WE CALL IT optimisation these days, but what do you call it when a firm over optimises? We used to call it something different in the days of the NV30, when Nvidia had to do something to make its chip work better and do better in benchmarks but to our surprise it seems to have done it again. The chaps from 3D Center, a very talented in-depth site, spotted and tested and proved that Nvidia is using a lower anisotropic filtering quality than any other card available.

Those guys noticed a texture shimmering problem when you are using normal driver settings. This was the case with NV40 cards but you could resolve this flickering by using high quality driver settings. This won't work on G70 based cards, so the guys well known for its thorough benchmarks went digging a little deeper into the chip.

It turns out that Nvidia is not doing anisotropic filtering the way it should and that the picture quality is the one to suffer. You will get the shimmering effect on your textures whenever you are using Geforce 7800GTX cards but you won't see this using Radeon cards.

The guys claimed that all NV40 and G70 cards will suffer from the same flickering problem and that these cards have "by far worse AF quality". They also add that Nvidia got the flickering because it was using general under sampling and as a result is getting the flickers. It's interesting to note that older Geforce 5800 Ultra won't suffer from this, just the new cards that 6800 or 7800 based.

Another German web site Computerbase , went a step further. It made a custom driver by changing the inf, where the driver could not recognise 7800GTX and use its optimisations. The card was listed as unknown but was working just fine. But when the guys went testing they noticed a massive performance drop when using those drivers, close to 30 percent and related it to anisotropic filtering. Nvidia has a lot to explain.

3DCenter, for the original article, is here in English while the Computerbase German article is here. We will ask Nvidia what is going on but we think there's something up. At lease the guys proved it isn't a hardware bug - it's a driver problem only but performance drops dramatically as soon as you resolve it. µ


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