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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StevoLincolnite - Wednesday, June 25, 2008 - link
Of course it can, There are benchmarks isn't there?Seriously ANY Direct X 9 card can run Crysis, The Quality and Performance is a different matter.
Inkjammer - Wednesday, June 25, 2008 - link
I have a 9800 GX2 in my primary gaming rig, but I've been debating on what card to drop into my Photoshop/3DS Max art rig. I've been waffling over it for some time, and was going to settle on an 8800GT... but after seeing this, my mind's set on the 4850. It definitely appears to offer more than enough power to handle my art apps, and allow me to use my second PC a gaming rig if need be... all without breaking the bank.This'll mark my return to buying ATI hardware since the X800 was king.
weaksideblitz - Wednesday, June 25, 2008 - link
this is a welcome development although im only buying a 4850 :)Locutus465 - Wednesday, June 25, 2008 - link
Very much so, actually from where I sit I think all AMD really needs to do is get a SAM2+ CPU out there that can compete with intel at least similarly to how this card competes with nvida and they'd have one hell of a total platform solution right now. As for upgrading my vid card... I just finished upgrading to the Phenom 4x and Radeon 3870 so I'll be sticking with that for a while. Quite honestly that platform can pretty much run anything out there already as it is, so I'm feeling pretty confident my current setup will last a couple years at least.Lifted - Wednesday, June 25, 2008 - link
Ditto. If I can get a 4850 for ~$150 or so, that's what I'm doing as well.billywigga - Friday, August 29, 2008 - link
where are you getting it from best buy or somethingClauzii - Wednesday, June 25, 2008 - link
That leaves 50 for a better cooler ;)Lifted - Wednesday, June 25, 2008 - link
Is there any reason the first pages of benchmarks have SLI setups included in the charts, but you wait until the end of the article to add the CF? I'd think it would make the most sense to either include both from the start or hold both until the end.Anand Lal Shimpi - Wednesday, June 25, 2008 - link
The original idea was to format it like the 4850 preview, keep things simple early on but offer SLI/CF graphs later in the article for those who wanted them.It looks like in the mad rush to get things done it didn't work out that way, I'll see if it's possible to clean it all up but right now we've got a lot of other minor touchups to do first :)
Take care,
Anand
TechLuster - Wednesday, June 25, 2008 - link
Anand,I really like your idea of "keeping things simple early on" by only including configurations that us mere mortals can afford at first (say, all single-GPU configs plus "reasonable" multi-GPU configs less than ~$400 total), and then including numbers for ultra high-end multi-GPU configs at the end (mainly just for completeness and also for us to drool over--I doubt too many people can afford more than one $650 card!).
Anyway, great job on the review as always. I think you and Derek should get some well-deserved rest now!
-TL