Blizzard said:
Hey brain_stew, I have a question, and hopefully this is the appropriate thread (I think you mentioned it here, maybe?). Someone, possibly you, said that AF (anisotropic filtering) has little to no performance hit. Testing in Trine, as I posted in the demo thread, the first little section of the thief's area has drops to 50 fps or so if I have AF set to 8, and stays 67 through most of it (until the foggy area) if I have AF disabled. Does this sound reasonable for a 4850, and if so, what's a reasonable compromise to prevent AF from causing too much of a hit? I typically pick 2AA, 2AF for games if they play smoothly that way, and I didn't try turning up AF until you suggested it.
The problem is that you can't really make one sweeping generalisation, as it will be different in every game and with every GPU.
Generally AF has a very small hit in modern games on modern hardware, but it depends how your hardware is being worked. If for instance, you're shader bound, you may find that enabling even 16xAF has zero impact on your framerates. However, since AF is very bandwidth intensive, if you're rendering at a high resolution and the game engine taxes your card's bandwidth then you might see performance take a nosedive.
The 4850 that you're using is bandwidth starved, so its not surprising that AF causes a bigger hit on the card than others. The 4870 which is just one step up on the ladder and uses the same core architecture has close to twice the bandwidth. At low resolutions and low IQ settings the 4850 and 4870 are very equal, but once you crank up the resolution, and the AA/AF, the 4870 speeds ahead. The smaller RAM pool on your card may also be a factor.
I have to say in my experience with the demo I found performance suddenly dropped very harshly between 2x multisampling where I got a rock solid 60fps without a single dropped frame to 4x multisampling where seemingly sporadically my framerate would tank by 15fps every now and then, so the game may be very bandwidth intensive.
I'd suggest having a bit more of a fiddle, try using only high textures, make sure the multisampling is turned off and see what that does for performance. I find that each AF setting has a huge impact on visuals and texture clarity upto 8x, after which the difference is very ahrd to spot so I don't bother with 16x much at all yet force 8x in every game pretty much.
If you're a big whore for resolution and general IQ then I think you'd see the benefit in a card with a larger framebuffer, and oodles of bandwidth to spare like the GTX 260 (216) or 4890. The 4850 and 8800GT and cards of that ilk are really tremedous performers at lower resolutions but they were just no meant for high resolutions and high IQ, its inherant in their design. That's why performance can often tank when you go crazy on them settings.
Blizzard said:
Thanks, but do you mind responding to my AF post if you get a chance? :/
I only spotted your query when I came to post that link!
Give me a chance I'm only human!! :lol :lol
) and EVGA's excellent 90 day stepup program, along with the large boost in performance, it seems a nice deal to me:
