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
AMD's "Small-Die" Strategy
We outlined AMD's "new" GPU strategy in our Radeon HD 4850 preview article, but in short AMD has committed to designing GPUs for the mainstream $199 - $299 segment and simply using CrossFire (multi-GPU) to address higher end markets. NVIDIA on the other hand will continue to make very large monolithic GPUs in order to continue to push the industry forward. Both approaches are appreciated and necessary, they simply target different markets.
In our GT200 review we highlighted the fact that NVIDIA had built an extremely large, highly parallel, microprocessor. With 1.4 billion transistors and a die size of around 576 mm^2, NVIDIA's GT200 is nothing short of huge.
The table on the previous page shows that AMD's RV770, despite being aimed at mainstream gamer price points ($199 - $299), is also very large. At 956M transistors, the RV770 has 44% more transistors than RV670 and 68% the transistor count of NVIDIA's GT200. We threw the RV770 into NVIDIA's die size comparison just for kicks:
Based on what we know of NVIDIA's die size, this should be to scale
Even AMD's die, although designed to be svelte and affordable, is big - especially for being fabbed at TSMC. NVIDIA still holds the crown for largest die fabbed at TSMC, but AMD shows us that even a more mainstream approach still requires tons of transistors. As we mentioned in our 4850 preview:
"A pair of RV770s, AMD's new GPU, end up consuming more power than a single GT200 - despite being built on a smaller 55nm process.
A pair of these RV770s only costs $400 compared to $650 for a single GT200, but I suspect that part of that is due to differences in manufacturing process. If NVIDIA hadn't been so risk averse with the GT200 and built it on 55nm (not that I'm advocating it, simply posing a hypothetical), the cost differences would be smaller - if not in favor of NVIDIA since GT200 is built on a single card.
When the smoke clears, AMD's strategy is to simply build a GPU for the masses and attempt to scale it up and down. While NVIDIA is still building its GPUs the same way it has for decades, starting very large and scaling down.
AMD isn't taking a radically different approach to building and designing GPUs than NVIDIA, it's simply building one market segment lower."
We've got a lot of discussion on efficiency between AMD and NVIDIA coming up in this article, although AMD's die is noticeably smaller than NVIDIA's - as you've already seen with the Radeon HD 4850 - there are many areas where RV770 can go toe-to-toe with NVIDIA's mammoth GT200.
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0g1 - Wednesday, June 25, 2008 - link
In the article it says the GT200 doesn't need to do ILP. It only has 10 threads. Each of those threads needs ILP for each of the SP's. The problem with AMD's approach is each SP has 5 units and is aimed directly at processing x,y,z,w matrix style operations. Doing purely scalar operations on AMD's SP's would be only using 1 out of the 5 units. So, if you want to get the most out of AMD's shaders, you should be doing vector calculations.DerekWilson - Wednesday, June 25, 2008 - link
The GT200 doesn't worry with ILP at all.a single thread doesn't run width wise across all execution units. instead different threads execute the exact same single scalar op on their own unique bit of data (there is only one program counter per SM for a context). this is all TLP (thread level parallelism) and not ILP.
AMD's compiler can pack multiple scalar ops into a 5-wide VLIW operation.
on purely scalar code with many independent ops in a long program, AMD can fill all their units and get close to peak performance. explicit vector instructions are not necessary.
gigahertz20 - Wednesday, June 25, 2008 - link
http://www.hardwarecanucks.com/forum/hardware-canu...">http://www.hardwarecanucks.com/forum/ha...870-512m...The site above mounted an after market cooler on it and got awesome results. Either the Thermalright HR-03 GT is just that great of a GPU cooler, or the standard heatsink/fan on the 4870 is just that horrible. Going from 82C to 43C at load and 55C to 33C at idle, just from an after market cooler is crazy! I was hoping to see some overclocking scores after they mounted the Thermalright on it, but nope :(
Matt Campbell - Wednesday, June 25, 2008 - link
The HR-03GT really is that great. Check it out: http://www.anandtech.com/casecoolingpsus/showdoc.a...">http://www.anandtech.com/casecoolingpsus/showdoc.a...Our 8800GT went from 81 deg. C to 38 deg. C at load, 52 to 32 at idle. That's also with the quietest fan on the market at low speed. And FWIW, I played through all of The Witcher (about 60 hours) with the 8800GT passively cooled in a case with only 1 120mm fan.
-Matt
Clauzii - Wednesday, June 25, 2008 - link
I see no fan on that thing??! PASSIVE?? :O ??jeffreybt2 - Wednesday, June 25, 2008 - link
"Please note that this is with a single Zalman 92MM fan operating at 1600RPM along with Arctic Cooling MX-2 applied to the base."magnusr - Wednesday, June 25, 2008 - link
Does the audio part of the card support PAP? If not all blu-ray audio will be downsampled to 16/48...NullSubroutine - Wednesday, June 25, 2008 - link
I would just like to point out that the 4870 falls behind the 3870 X2 in Oblivion while in every other game it runs circles around it. To me it appears to be a driver problem with Oblivion rather than an indication of the hardware not doing well there. Unless of course the answer lies in the ring bus of the R680?orionmgomg - Wednesday, June 25, 2008 - link
I would love to see more benchmarks with the CPU OCed to at least 4.0All the CPUs you use can hit it NP.
Also, what about at least 2 GTX 280 Cards and their numbers. Noticed that you did have them in SLI cause the power comsumption comparisons had them, but you held back the performance numbers...
Lets see the top 4 cards from ATI and Nvidia compete in dule GPU (no punt intended)on an X48 with DDR3 1600 and a FSB of 400x10!
That would be really nice for the people hoe have performance systems, but may still be rocking out a pair of EVGA 8800Ultras, cause their waiting for real numbers and performance to come out - and their still paying off theye systems lol... :]
Ilmarin - Wednesday, June 25, 2008 - link
You're probably aware of these already, but I'll mention them just in case:* Page 10 (AA comparison) is malformed with no images
* Page 21 (Power, Heat and Noise) is missing the Heat and Noise stuff.
Heat is a big issue with these 4800 cards and their reference coolers, so it would be good to see it covered in detail. My 7800 GTX used to artifact and cause crashes when it hit 79 degrees, before I replaced it with an aftermarket cooler. Apparently the 4870 hits well over 90 degrees at load, and the 4850 isn't much better. Decent aftermarket coolers (HR-03 GT, DuOrb) aren't cheap... and if that's what it takes to prevent heat problems on these cards, some people might consider buying a slower card (like a 9800 GTX+) just because it has better cooling.
Anand, you guys should do a meltdown test... pit the 9800 GTX+ against the 4850, and the 4870 against the GTX 260, all with reference coolers, in a standard air-cooled system at a typical ambient temp. Forget timedemos/benchmarks... play an intensive game like Crysis for an hour or two, and see if you encounter glitches and crashes. If the 4800 cards can somehow remain artifact/crash free at those high temps, then I'd more seriously consider buying one. Heat damage over time may also be a concern, but is hard to test for.
Sure, DAAMIT's partners will eventually put non-reference coolers on some cards, but history tells us that the majority of the market in the first few months will be stock-cooled cards, so this has got be of concern to consumers... especially early adopters.