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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Amiga500 - Wednesday, June 25, 2008 - link
Apple has passed over control of Open CL to the Khronos group, which manage open sourced coding.To all intentions and purposes, it is open source. :-)
emergancyexit - Wednesday, June 25, 2008 - link
i hope you do 3x crossfire can do. maybe a 4x 4850 vs 3x GTX 260 just to satisfy us readers for the moment would be lovely!DerekWilson - Wednesday, June 25, 2008 - link
i'm not sure if this is supported out of the box ... ill have to check it out ...emergancyexit - Wednesday, June 25, 2008 - link
i would really like to know what type of performance theese cards could get in an MMO. (and hopefully compare them to some cheaper cards) Games im interested in are some of the newer titles like Age of conan ( i hear it's graphics are great and is a workout for even a 8800 ultra) And Eve-online (thier new graphics engine works cards pretty hard too)MMO's Graphics usually get pretty intesive with some odd 200+ characters flying around shooting fireballs evrywhere with missles sailing through the air in a land of hundreds of monsters as far as the eye can see. it can get pretty demanding on a gameing computer, just as much (if not more) as a hit new title.
for example, on my current Rig i can get around 50FPS steady at 1440x900 but on Eve-Online i get 35 at the most at peacefull times and 20 or even 15 in a large fight with FEW graphics options selected.
MIP - Wednesday, June 25, 2008 - link
Great review, the 4870 looks to be fantastic value. However, we're missing the 'heat and noise' part.skiboysteve - Wednesday, June 25, 2008 - link
Not only do these cards rock, but I wouldn't be surprised if AMD has an ace up its sleeve with the 4870x2... with that crossfire interconnect directly connected to the data hub that you showed on the chart. That and the fact that they have been looking forward to this crossfire strategy of attacking the high end for quite some time so they might have some tricky driver stuff coming with it.I have been disappointed with the heat and power consumption of these cards. But:
1) Someone said powerplay is getting a driver tweak and, I can always clock them lower in 2D than 500/1000 (which is insane for 2d)
2) That hardware site someone linked earlier showed a more than 50% reduction in temperatures with an aftermarket cooler! Thats insane!!
And finally, if I can get the 1 & 2 fixed... I want to know how well these babys overclock. If I can get a 4850 running like a 4870 or better... yum. And in that case, how high will a 4870 OC? And I want to know this with a non stock cooler, because apparently the stock ones suck. With a non stock cooler if the 4850 clocks up to 4870 level, but the 4870 clocks way up too... i'm gonna have to grab a 4870.
So yeah, fix #1 and #2 and find me non-stock cooler OC #s and I'll go buy one (maybe two?) when nehalem comes out
Powered by AMD - Wednesday, June 25, 2008 - link
Impressive review, Thanks :)A few glitches:
It says "Power Consumption, Heat and Noise", but the graphs only shows Power Consuption.
In Page 17 (The Witcher), in second paragraph, it says 390X2 instead of 3870.
Thanks again.
Cheers from Argentina.
Conscript - Wednesday, June 25, 2008 - link
atleast that was the tile of the second to last page...but only see two power consumption graphs?Proteusza - Wednesday, June 25, 2008 - link
I quote one Kristopher Kubricki regarding whether the RV770 is inferior to the GT200:"It is. Even AMD isn't going to tell you otherwise. You can debate this all you want, but it's still a $200 video card."
So, please tell me now why I should pay $650 for a GTX280. I'm struggling to see the logic here.
Source: http://www.dailytech.com/Update+AMD+Preps+Radeon+4...">http://www.dailytech.com/Update+AMD+Pre...50+Launc...
(near the bottom)
AbRASiON - Wednesday, June 25, 2008 - link
I can live with a greedier card than my 8800GT but I refuse to put up with a noisy machine.Any comments on the heat and noise please? would be nice!