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
Fixing AMD's Poor AA Performance
Now that we have a new architecture from AMD with improved AA performance, it's time again to look at a comparison of all the different AA modes these cards offer. No new modes have been introduced since the R600 and G80 reviews, but AMD has completely rebuilt their ROPs with special attention to hardware based AA resolve. In R600, hardware resolve wasn't much faster than shader based resolve, but this time around, AA runs blazingly fast whether its on the dedicated resolve hardware or on the shader hardware (since their is so much more shader hardware now even shader based resolve gets a giant boost).
The first thing we will want to look at are the MSAA modes. These are the modes we absolutely recommend for use with AMD hardware as all their other filters essentially low-pass filter the entire image by blending in neighboring subpixels. In any case, the results are very impressive for RV770.
The RV670 at 19x12 was limited in some way other than AA (it really couldn't keep up), but at 16x10 we can get a better idea of relative impact of AA. And clearly the RV770 quite improves fall off with increasing AA levels over the previous generation. One special thing to note is that the RV770 does fall off very gracefully to 8xAA. Since the RV670, G80 and GT200 all have sharp drops in performance when moving up from 4xAA to 8xAA, the RV770 really shines here. In fact, the few tests we did with 8xAA paints the 4870 in a much better light relative to the GTX 280. Remember from our earlier architecture discussion that Oblivion is the game where the GT200 had the largest performance advantage over RV770.
While 8xAA performance is all well and good, the image quality difference is just not enough for us to recommend enabling it over increasing resolution (or better yet, pixel density on LCD panels -- hello display makers). For those with panels that don't go over 1280x1024, it would be better to spend the extra money on a large panel than a $300 graphics card. The application where we see 8xAA making the most sense is on 50+ HDTVs used as computer monitors where the pixels are just plain huge. For the majority of desktop users though 4xAA is where it's at.
We did test the performance of all the other modes as well. NVIDIA's CSAA modes are quite good (they actually improve image quality rather than degrade it), but again, stay away from anything but AMD's "box" filtered AA.
The RV770 actually shows a bigger performance hit from enabling their tent filters than RV670. This is likely because the filters are run on shader hardware in both cases while RV770 has faster hardware resolve that can be used for normal AA resolve. If RV670 resolves "box" filtered AA on the shader as well this would explain the flatter performance in that case. Even more so than the image quality question, the fact that they perform lower really should be the nail in the coffin for AMD's tent filter garbage.
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jALLAD - Wednesday, July 9, 2008 - link
well I am looking forward to a single card setup. SLI or CF is beyond the reach of my pockets. :PGrantman - Friday, July 4, 2008 - link
Thank you very much for including the 8800gt sli figures in your benchmarks. I created an account especially so I could thank Anand Lal Shimpi & Derek Wilson as I have found no other review site including 8800gt sli info. It is very interesting to see the much cheaper 8800gt sli solution beating the gtx 280 on several occasions.Grantman - Friday, July 4, 2008 - link
When I mentioned "no other review site including 8800gt sli info" I naturally meant in comparison with the gtx280, gx2 4850 crossfire etc etc.Thanks again.
ohodownload - Wednesday, July 2, 2008 - link
computer-hardware-zone.blogspot.com/2008/07/ati-radeon-hd4870-x2-specification.tml
DucBertus - Wednesday, July 2, 2008 - link
Hi,Nice article. Could you please add the amount of graphics memory on the cards to the "The Test" page of the article. The amount of memory matters for the performance and (not unimportant) the price of the cards...
Cheers, DucBertus.
hybrid2d4x4 - Sunday, June 29, 2008 - link
Hello!Long-time reader here that finally decided to make an account. First off, thanks for the great review Anand and Derek, and hats off to you guys for following up to the comments on here.
One thing that I was hoping to see mentioned in the power consumption section is if AMD has by any chance implemented their PowerXpress feature into this generation (where the discrete card can be turned off when not needed in favor of the more efficient on-board video- ie: HD3200)? I recall reading that the 780G was supposed to support this kind of functionality, but I guess it got overlooked. Have you guys heard if AMD intends to bring it back (maybe in their 780GX or other upcoming chipsets)? It'd be a shame if they didn't, seeing as how they were probably the first to bring it up and integrate it into their mobile solutions, and now even nVidia has their own version of it (Hybrid Power, as part of HybridSLI) on the desktop...
AcornArmy - Sunday, June 29, 2008 - link
I honestly don't understand what Nvidia was thinking with the GTX 200 series, at least at their current prices. Several of Nvidia's own cards are better buys. Right now, you can find a 9800 GX2 at Pricewatch for almost $180 less than a GTX 280, and it'll perform as well as the 280 in almost all cases and occasionally beat the hell out of it. You can SLI two 8800 GTs for less than half the price and come close in performance.There really doesn't seem to be any point in even shipping the 280 or 260 at their current prices. The only people who'll buy them are those who don't do any research before they buy a video card, and if someone's that foolish they deserve to get screwed.
CJBTech - Sunday, June 29, 2008 - link
Hey iamap, with the current release of HD 4870 cards, all of the manufacturers are using the reference ATI design, so they should all be pretty much identical. It boils down to individual manufacturer's warranty and support. Sapphire, VisionTek, and Powercolor have all been great for me over the years, VisionTek is offering a lifetime warranty on these cards. I've had poor experiences with HIS and Diamond, but probably wouldn't hesitate to get one of these from either of those manufactures on this particular card (or the HD 4850) because they are the same card, ATI reference.Paladin1211 - Saturday, June 28, 2008 - link
Now that the large monolithic, underperforming chip is out, leaving AMD free to grab market share, I'm so excited at what to happen. As nVidia's strategy goes, they're now scaling down the chip. But pardon me, cut the GTX 280 in half and then prices it at $324.99? That sounds so crazy!Anyone remembers the shock treatment of AMD with codename "Thunder"? DAAMIT has just opened "a can of whoop ass" on nVidia!
helldrell666 - Friday, June 27, 2008 - link
Anand tech why didnt you use and amd 790FX board to bench the radeon cards instead of using an nvidia board for both nvidia and ATI cards.It would be more accurate to bench those cards on compatible boards .I think those cards would have worked better on an amd board based on the radeon express 790fx chipset.