The Radeon HD 4850 & 4870: AMD Wins at $199 and $299
by Anand Lal Shimpi & Derek Wilson on June 25, 2008 12:00 AM EST- Posted in
- GPUs
AA Comparison
And now the fun part: playing around with images. Certainly everyone has their own taste when it comes to AA, but we've cropped and blown up this 800x600 screenshot from Oblivion in order to better show what's really going on. As resolution increases and pixel size decreases, the impact of higher AA modes also decreases. This is useful to keep in mind here.
A few key points to check out: compare the interior of textures between either no AA image and any of AMD's tent filters. Notice how the detail on interior textures is significantly decreased. It can be quite frustrating to enable a high anisotropic filtering level to increase the detail of textures only to find them blurred by your AA mode. Also, note how NVIDIA's 8x CSAA and 16x CSAA modes only subtly change some of the pixels. This is because CSAA actually attempts to better understand the actual geometry that a pixel covers rather than going around looking for data outside the pixel to bring in.
These screenshots are with gamma correction enabled on NVIDIA hardware in order to give the best comparison with RV770 which does not allow us to disable gamma correction. We do prefer disabling gamma correction for the average case and especially for anti-aliasing thin lines.
Click the links in the table below to change the AA images displayed
AMD RV770 |
NVIDIA GT200 |
Click here to download all the full resolution, uncompressed images used in this comparison
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DerekWilson - Wednesday, June 25, 2008 - link
it looks like the witcher hits an artificial 72fps barrier ... not sure why as we are running 60hz displays, but that's our best guess. vsync is disabled, so it is likely a software issue.JarredWalton - Wednesday, June 25, 2008 - link
Again, try faster CPUs to verify whether you are game limited or if there is a different bottleneck. The Witcher has a lot of stuff going on graphically that might limit frame rates to 70-75 FPS without a 4GHz Core 2 Duo/Quad chip.chizow - Wednesday, June 25, 2008 - link
It looks like there seems to be a lot of this going on in the high-end, with GT200, multi-GPU and even RV770 chips hitting FPS caps. In some titles, are you guys using Vsync? I saw Assassin's Creed was frame capped, is there a way to remove the cap like there is with UE3.0 games? It just seems like a lot of the results are very flat as you move across resolutions, even at higher resolutions like 16x10 and 19x12.Another thing I noticed was that multi-GPU seems to avoid some of this frame capping but the single-GPUs all still hit a wall around the same FPS.
Anyways, 4870 looks to be a great part, wondering if there will be a 1GB variant and if it will have any impact on performance.
DerekWilson - Wednesday, June 25, 2008 - link
the only test i know where the multi-gpu cards get past a frame limit is oblivion.we always run with vsync disabled in games.
we tend not to try forcing it off in the driver as interestingly that decrease performance in situations where it isn't needed.
we do force off where we can, but assassins creed is limiting the frame rate in absentia of vsync.
not sure about higher memory variants ... gddr5 is still pretty new, and density might not be high enough to hit that. The 4870 does have 16 memory chips on it for its 256-bit memory bus, so space might be an issue too ...
JarredWalton - Wednesday, June 25, 2008 - link
Um, Derek... http://www.anandtech.com/video/showdoc.aspx?i=3320...">I think you're CPU/platform limited in Assassin's Creed. You'll certainly need something faster than 3.2GHz to get much above 63FPS in my experience. Try overclocking to 4.0GHz and see what happens.weevil - Wednesday, June 25, 2008 - link
I didnt see the heat or noise benchmarks?gwynethgh - Wednesday, June 25, 2008 - link
No info from Anandtech on heat or noise. The info on the 4870 is most needed as most reviews indicate the 4850 with the single slot design/cooler runs very hot. Does the two slot design pay off in better cooling, is it quiet?DerekWilson - Wednesday, June 25, 2008 - link
a quick not really well controlled tests shows the 4850 and 4870 to be on par in terms of heat ... but i can't really go more into it right now.the thing is quiet under normal operation but it spins up to a fairly decent level at about 84 degrees. at full speed (which can be heard when the system powers up or under ungodly load and ambient heat conditions) it sounds insanely loud.
legoman666 - Wednesday, June 25, 2008 - link
I don't see the AA comparisons. There is no info on the heat or noise either.DerekWilson - Wednesday, June 25, 2008 - link
the aa comparison page had a problem with nested quotes in some cases in combination with some google ads on firefox (though it worked in safari ie and opera) ...this has been fixed ...
for heat and noise our commentary is up, but we don't have any quantitative data here ... we just had so much else to pack into the review that we didn't quite get testing done here.