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
One, er, Hub to Rule them All?
With R500 AMD introduced its first ring bus, a high speed, high bandwidth bus designed to move tons of data between consumers of memory bandwidth and the memory controllers themselves. The R600 GPU saw an updated version of the ring bus, capable of moving 100GB/s of data internally:
On R600 the ring bus consisted of two 512-bit links for true bi-directional operation (data could be sent either way along the bus) and delivered a total of 100GB/s of internal bandwidth. The ring bus was a monster and it was something that AMD was incredibly proud of, however in the quest for better performance per watt, AMD had to rid itself of the ring and replace it with a more conventional switched hub architecture:
With the ring bus data needed to be forwarded from one ring stop to the next and all clients got access to the full bandwidth, regardless of whether or not they needed it. For relatively low bandwidth data (e.g. UVD2 and display controller data), the ring bus was a horrible waste of power.
With the RV770 all that exists is a simple switched hub, which means that sending data to the display controller, PCIe and UVD2 (AMD's video decode engine) traffic are now far less costly from a power standpoint. Another side effect of ditching the ring bus is a reduction in latency since data is sent point to point rather than around a ring. With the move to a hub, AMD increased their internal bus width to 2kbits wide (which is huge). Maximum bandwidth has increased to 192GB/s (in 4870) but this depends on clock speeds.
With nearly double the internal bandwidth and a point to point communication system, latency between memory clients should be decreased, and huge amounts of data can move between parts of the chip. Certainly getting enough data on to the GPU to feed 800 execution units is a major undertaking and AMD needed to make a lot of things wider to accommodate this.
The CrossFire Sideport
Although AMD isn't talking about it now, the CrossFire Sideport is a new feature of the RV770 architecture that isn't in use on the RV770 at all. In future, single-card, multi-GPU solutions (*cough* R700) this interface will be used to communicate between adjacent GPUs - in theory allowing for better scaling with CrossFire. We'll be able to test this shortly as AMD is quickly readying its dual-GPU RV770 card under the R700 codename.
One thing is for sure, anything AMD can do to assist in providing more reliable consistent scaling with CrossFire will go a long way to help them move past some of the road blocks they currently have with respect to competing in the high end space. We're excited to see if this really makes a difference, as currently CrossFire is performed the same way it always has been: by combining the output of the rendered framebuffer of two cards. Adding some sort of real GPU-to-GPU communication might help sort out some of their issues.
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paydirt - Wednesday, June 25, 2008 - link
This is a review site. This isn't a site to market/promote products.formulav8 - Thursday, June 26, 2008 - link
They do recommend hardware for different price points and such. So they do market in a way. Have you seen anands picks links? That is promoting products and does it through his referral links as well to get paid to do so. :)Anyways, mentioning something as a better buy up to a certain price point would be helpful to someone who is not really in the know.
Jason
shadowteam - Wednesday, June 25, 2008 - link
You've got excellent written skills buddy, and I can't help thinking you're actually better at reviews than your m8 (no offence Anand), but what I truly meant from my post above is what you summed up rather well in your conclusive lines, quote: "You can either look at it as AMD giving you a bargain or NVIDIA charging too much, either way it's healthy competition in the graphics industry once again (after far too long of a hiatus)"Either way? Why should anyone look the other way? NV is clearly shitting all over the place, and you can tell that from the email they send you (or Anand) a couple days back. So they ripped us off for 6 months, and now suddenly decide the 9800GTX is worth $200?
Healthy competition? Could you please elaborate on this further?
$199 4850 vs $399 GTX260.... yup! that's healthy
GTX+ vs 4850?
Does that mean the GTX260 is now completely irrelevant? In fact, the 2xx series is utterly pointless no matter how you look at it.
To bash on AMD, the 4870 is obviously priced high. For $100 extra, all you get is an OC'ed 4850 w/ DDR5 support. I don't think anyone here cares about DDR5, all that matters is performance, and the extra bucks plainly not worth it. From a consumers' perspective, the 4850 is the best buy, the 4870 isn't.
mlambert890 - Sunday, July 13, 2008 - link
"200 series is utterly pointless"Yep... pointless unless you want the fastest card (280), then it has a point.
Pointless to YOU possibly because you're focusing on perf per dollar. Good for you. Nice of you to presume to force that view on the world.
Absolute performance? GTX 280 seems near the top of every benchmark there bud. Both in single card and in SLI where, last I checked, it gives up maybe TWO instances to the 4870CF - Bioshock and CoD and in both cases framerates are north of 100 at 2560. The 4870, on the other hand, falls WELL short of playable at that res in CF in most other benches.
High res + high perf = 200 series. Sorry if thats offensive to the egos of those who cant afford the cards.
Theres a lot in life we can and cant afford. Should have ZERO impact on ABSOLUTE PERFORMANCE discussions.
FITCamaro - Wednesday, June 25, 2008 - link
AMD/ATI has to make some money somewhere. And regardless, at $300, the 4870 is a hell of a deal compared to the competition. Yes the 4850 is probably the best value. But the 4870 is still right behind it if you want a decent amount of extra performance at a great price.Nvidia may have the fastest thing out there. But only the richest, most brain dead idiots who have not a care in the world about how they spend their (or their parents) money will buy it with cards like the 4850 and 4870 available.
And its pretty sad when your new $650 high end card is routinely beat by two of your last generation cards (8800GT) that you can get for $150 each or less. It wouldn't be as big a deal if the new card was $300-350 but at $650, it should be stomping on it.
I think Nvidia is in for a reality check for what people want. If their new chips are only going to cater to the top 1% of the market, they're going to find themselves quickly in trouble. Especially with the all the issues their chipsets have for 6 months after release. And their shoddy drivers. I mean this past Friday I decided to try and set up some profiles so that when I started up Age of Conan, it would apply an overclock to my GPU and unapply it after I exited, it ended up locking up my PC continuously. I had to restore my OS from a backup disc because not even completely uninstalling and reinstalling my nvidia chipset and video drivers fixed it. And in my anger, I didn't back up my "My Documents" folder so I lost 5 years worth of stuff, largely pictures.
mlambert890 - Sunday, July 13, 2008 - link
"Nvidia may have the fastest thing out there. But only the richest, most brain dead idiots who have not a care in the world about how they spend their (or their parents) money will buy it with cards like the 4850 and 4870 available."You just summed it up in that first sentence there bud. NVidia has the fastest thing out there. The rest is just opinion, bitterness and noise.
I notice that the tone of the "enthusiast" community seems to be laser focused on cost now. This is like car discussions. People want to pretend to be "Xtreme" but what they really want to see is validation of whatever it is THEY can afford.
Have fun with the 4870 by all means, its a great card. But the GTX280 IS faster. Did NVidia price it too high? Dont know and dont care.
These are PERFORMANCE forums to all of the people that dont get that. Maybe even the editors need to be reminded.
If I want to see an obsession with "bang for the buck" Ill go to Consumer Reports.
I mean seriously. How much of a loser are you when you're taking a shot like "your PARENTS money"? LOL...
Personally, I treat the PC hobby as an expensive distraction. Ive been a technology pro for 15 years now and this is my vice. As an adult earning my own money, I can decide how I spend it and the difference between $500 and a grand isnt a big deal.
The rehtoric on forums is really funny. People throw the "kid/parents" insult around alot, but I think its more likely that the people who take prices beyond what they can afford as some kind of personal insult are more likely the kids here.
formulav8 - Thursday, June 26, 2008 - link
"Nvidia may have the fastest thing out there. But only the richest, most brain dead idiots who have not a care in the world about how they spend their (or their parents) money will buy it with cards like the 4850 and 4870 available."Yuk Yuk Yuk :)
Jason
drpepper128 - Wednesday, June 25, 2008 - link
To be honest, while I was reading the article I felt as if the article seemed a little ATI biased, but I guess that goes to show you that two different people can get drastically different opinions from the same article.The real reason I’m posting this is I want to thank you guys for writing some of the best articles that Anandtech has ever written. I read every page and enjoyed the whole thing. Keep up the great work guys and I look forward to reading more (especially about Nehalem and anything relating to AMD’s future architecture).
Also, is GDDR5 coming to the 4850 ever? If so, maybe it would be a drastically better buy.
Thank you,
drpepper128
Clauzii - Wednesday, June 25, 2008 - link
Damn, You R pissed!! :OOK, get some sleep and wake up smiling tomorrow, knowing that It's ATI needing to raise prices - - - and go get that 4870 :))
Clauzii - Wednesday, June 25, 2008 - link
OH, " ... that It's NOT ATI needing to ... "BTW: I actually read the review as pretty neutral, making a hint here and there that the further potential of the HD4870 is quite big :)