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AMD Radeon HD 3870/3850 Performance Preview November 14, 2007 |
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Summary: AMD’s RV670 GPU is finally here in the form of the Radeon HD 3800 series. The Radeon 3870 and 3850 feature 320 stream processors, DirectX 10.1 and PCI Express 2.0 support, as well as 4-Way CrossFire. Find out how these boards perform in this article!
 AMD Radeon HD 3870/3850 Performance Preview | Page:: ( 1 / 17 ) |
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While graphics manufacturers like to tout all the technology and performance offered by their flagship high-end graphics cards, it’s the mainstream segment of the graphics market that really moves the bulk of shipments for AMD and NVIDIA in a given month. OEMs like Dell and HP buy these cards by the truckload for use in affordable PCs, while gamers like you and me daydream of owning GeForce 8800 Ultra and Radeon HD 2900 XTs, but actually end up buying 8800 GTs and 2600 XTs in much larger quantities: while there are tens of thousands of enthusiasts willing to fork over $400 or more on a graphics card in a given financial quarter, there are hundreds of thousands who spend $150-$300 on their latest graphics upgrade in that same 3-month time span.
Unfortunately for AMD, they really haven’t had anything to offer in the performance mainstream segment ranging from $200-$300. The Radeon HD 2600 XT carries a $150 MSRP, while the 2900 XT officially starts at $400, leaving a huge hole in AMD’s lineup between the $151-$399 price point.
In late September, AMD quietly unveiled the Radeon HD 2900 Pro and 2900 GT to the public. The release of these GPUs was important for AMD because it finally gave them competitively performing parts in this critical segment – the 2900 GT carried a $200 MSRP while the 2900 Pro sold for $250-$300 – but these cards offered too little, too late, to make much of an impact for AMD financially. Both the 2900 GT and 2900 Pro were only offered by a handful of board manufacturers and in very limited quantities; whenever a few cards would pop up for sale at an online retailer, they would quickly sell out.
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These 2900 Pro and GT cards were never meant to be the solution for AMD at the performance mainstream segment. It just wasn’t practical for AMD to offer these cards at such low price points. After all, the 2900 Pro and 2900 GT both used the exact same R600 GPU found in the high-end Radeon HD 2900 XT. The boards also used the same PCB and cooling found on the 2900 XT. For all intents and purposes, AMD was basically holding a closeout sale on R600 with these cards. AMD and their board partners were essentially taking cards that once sold for $400 and giving them away for $200-$300.
As you can imagine, this wasn’t a very effective way for AMD to make money.
AMD needed a real solution to the problem at the $200-$300 price point and they needed one fast: with the avalanche of new games coming out for the holidays, countless gamers and hardware enthusiasts will be upgrading their PCs over the next 30 days. To add insult to injury, NVIDIA just released the GeForce 8800 GT 512MB at the $250-$300 price point and the card sold out everywhere within hours of its release!
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Today’s introduction of the Radeon HD 3850 and Radeon HD 3870 are meant to address this issue. The GPUs are built around a new 55-nm manufacturing process, making them cheaper for AMD to manufacture. Yet both chips feature 320 stream processing units, just like the 2900 XT! Let’s see what else is new about these cards…
| The RV670 GPU | Page:: ( 2 / 17 ) |
At the heart of the Radeon HD 3850 and 3870 lies AMD’s brand new RV670 GPU. RV670 is built largely on the R600 GPU used today in the Radeon HD 2900 XT, the chip features 320 stream processors, just like R600, only it has been updated to include support for UVD, providing full HD decode for H.264 and VC-1. RV670 has also been updated to support DirectX 10.1 and PCI Express 2.0.
The following table summarizes the features found in the Radeon HD 3850 and Radeon HD 3870, and how they compare to AMD’s Radeon HD 2900 XT:
| AMD Radeon HD 2000 Series Comparison | |||
| Radeon HD 3870 | Radeon HD 3850 | Radeon HD 2900 XT | |
| # of Transistors | 666M | 666M | 700M |
| Manufacturing Process | 55-nm | 55-nm | 80-nm |
| # of Stream Processors | 320 | 320 | 320 |
| Texture Units | 16 | 16 | 16 |
| Render Back-ends (ROPs) | 16 | 16 | 16 |
| Core Clock Speed | 777MHz | 670MHz | 740MHz |
| Memory Clock Speed | 2.25GHz (Effective) | 1.80GHz (Effective) | 1.65GHz (Effective) |
| Memory Interface | 256-bit | 256-bit | 512-bit |
| Memory Bandwidth | 72.0 | 57.6 | 105.6 |
| Multiply-Add Math Processing Rate | 497 GigaFLOPS | 428 GigaFLOPS | 475 GigaFLOPS |
| System Bus Support | PCI Express 2.0 | PCI Express 2.0 | PCI Express 1.0/1.1 |
| DirectX Support | 10.1 | 10.1 | 10 |
| Tessellation Unit | Yes | Yes | Yes |
| UVD Support | Yes | Yes | No |
| PowerPlay Support | Yes | Yes | No |
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55-nm manufacturing process
As you can see in the chart above, the RV670 chip used in the Radeon HD 3870 and 3850 is built on TSMC’s 55-nm manufacturing process. Moving to a smaller process allows AMD to integrate all of the key features found in R600, including all 320 stream processors, and still manufacture the chip affordably. To further reduce costs, AMD even managed to remove unneeded transistors from R600; moving to a narrower 256-bit memory interface also helps reduce AMD’s manufacturing costs for RV670.
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As you can see in the image above, thanks to the 55-nm process, RV670 boasts a much smaller die: 192 square millimeters in RV670 versus R600’s 408 square millimeters. This allows AMD to get twice as many RV670 chips from a single silicon wafer in comparison to R600, assuming equal yields.
Another benefit of the smaller process is reduced power consumption. RV670 needs only one 6-pin PCIe power connector in order to operate. With lower power consumption, the chip also generates less heat. This allows AMD to cool the chip with just a single-slot heatsink/fan unit in the case of the Radeon HD 3850.
DirectX 10.1
AMD’s Radeon HD 3870 and 3850 are the first GPUs on the market to support DirectX 10.1, which will make its debut with the first service pack for Windows Vista sometime next year. DirectX 10.1 is an update to the original DirectX 10 spec released earlier this year with Windows Vista. The most notable addition to DirectX 10.1 is arguably support for real-time global illumination, which should allow developers to provide better lighting and shadows in their games.
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DirectX 10.1 also provides pre-defined AA sample patterns that all DX10.1 compliant cards must support. This ensures a more consistent minimum level of AA image quality across all DX10.1 cards regardless of manufacturer (board manufacturers are also free to use their own custom sample patterns for even better AA quality).
PCIe 2.0
RV670 fully supports PCIe 2.0. PCIe 2.0 offers double the bandwidth of PCIe 1.1; 8.0GB/sec in each direction, providing a total of 16GB/sec of total memory bandwidth.
PowerPlay and CrossFire X
In addition to the smaller manufacturing process AMD has added a new embedded power state controller to further address RV670’s power draw. This controller monitors the GPU’s command buffer to see how extensively the GPU is being used. If the GPU is only partially taxed, the power state controller can then power down parts of the chip that aren’t being used. According to AMD “engine and memory clocks, voltages, clock gating and other parameters can be altered” as needed.
This goes much further than previous solutions AMD has implemented, which adjusted these aspects dynamically based on what applications were currently running.
Another feature RV670 supports is 4-way CrossFire support. AMD refers to this as CrossFire X. With this feature, up to four RV670 cards can be used to run up to 8 monitors (AMD has a video of this up and running here on YouTube), or the cards can be connected together to deliver a performance improvements of much greater than 2X. AMD will even provide the ability to independently overclock all four cards.
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AMD will be providing a beta CrossFire X driver sometime next month, and we’ll see an official WHQL release by the end of January 2008.
How does RV670 stack up against G92?
The G92 GPU inside NVIDIA’s GeForce 8800 GT will be going head-to-head with the RV670 chip inside Radeon HD 3870/3850. As such, we’re sure many of you are curious to see how the two GPUs stack up against one another, as well as their predecessors. The following chart summarizes things nicely:
| Mainstream GPU Comparison | |||||
| Radeon HD 3870 | GeForce 8800 GT | Radeon HD 3850 | GeForce 8600 GTS | Radeon HD 2600 XT | |
| Core Clock Speed | 777MHz | 600MHz | 670MHz | 675MHz | 800MHz |
| Stream Processor Clock Speed | 777MHz | 1.5GHz | 670MHz | 1.45GHz | 800MHz |
| # of Stream Processors | 320 | 112 | 320 | 32 | 120 |
| Memory Clock | 2.25GHz | 1.8GHz | 1.8GHz | 1.0GHz | 1.1GHz |
| Memory Interface | 256-bit | 256-bit | 256-bit | 256-bit | 256-bit |
| Texture fill-rate (Gigatexels/sec) | 12.4 | 33.6 | 10.7 | 10.8 | 6.4 |
| Memory Bandwidth | 72.0 | 57.6GB/sec | 57.6GB/sec | 32GB/sec | 35.2GB/sec |
| Memory Size | 512MB GDDR4 | 512MB GDDR3 | 256MB GDDR3 | 256MB GDDR3 | 256MB GDDR4 |
| Board Power | 105W | 110W | 95W | 71W | 74W |
| MSRP | $220 | $250+ | $179 | $150 | $150 |
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Keep in mind that paper specs can often be deceiving, we saw this most recently with R600. With 320 stream processors, AMD clearly has more shading horsepower than NVIDIA on paper, although keep in mind that while NVIDIA has fewer shaders than AMD, they’re running significantly faster at 1.5GHz. NVIDIA’s GeForce 8800 GT also has more texturing horsepower than AMD. NVIDIA’s at a memory bandwidth disadvantage on paper, but also keep in mind that the GDDR4 memory used on the Radeon HD 3870 card runs at higher latencies than the GDDR3 used on the 8800 GT board.
| Board Analysis | Page:: ( 3 / 17 ) |
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As we mentioned on the previous page, AMD will be offering two RV670 boards at launch: the Radeon HD 3870 and the Radeon HD 3850. We’ll talk about the Radeon HD 3870 first…
The Radeon HD 3870 card
Previously codenamed “Gladiator”, as you can see in the images, AMD’s Radeon HD 3870 is a dual-slot graphics card. Keep in mind that this is the basic board design AMD will be using on their own Radeon HD 3870 cards, board partners are free to make their own modifications to the cooling, or other aspects of the board design.
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In fact for this launch AMD will be providing much more leeway at launch. We’ve been told that board partners like ASUS will be producing their own single-slot Radeon HD 3870 cards. AMD decided to go with a dual-slot cooler on their own board in order to deliver maximum cooling and the lowest thermals without having to resort to exotic cooling features like heat pipes.
AMD has come up with a brand new cooler to keep the Radeon HD 3870 cool. A large copper heatsink rests above the GPU, while a second heatsink cools the board’s memory modules and power circuitry. The card’s fan has also been improved over the Radeon HD 2900 XT and runs much quieter than its predecessor – thankfully noise levels are now comparable to NVIDIA’s GeForce 8800 GT/GTX cards, even under load.
The card’s fan will occasionally crank up to higher levels when it’s really being taxed (i.e. overclocking), but once the temps go down the fan’s RPMs will settle down to more reasonable levels. We think most enthusiasts will be quite pleased with the stock heatsink/fan cooling unit.
All RV670 cards continue to offer two dual-link DVI connectors and supports HDCP. AMD will also continue to bundle the board with two HDMI adapters which are capable of carrying both audio and video; a pass through cable isn’t needed to run audio.
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Radeon HD 3850 Card
Previously codenamed “Revival”, AMD’s Radeon HD 3850 is meant to service the $150-$200 market. As such, the card ships with lower clock speeds and therefore AMD relies on a single-slot cooler on their own reference board design. Again though, AMD’s board partners are completely free to make their own adjustments to the reference board design and cooling.
In fact, we’ve already received PowerColor’s high-end Radeon HD 3850 offering, which ships with a dual-slot heatsink/fan unit for improved cooling performance:
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You can also see in our shots of the PowerColor board that it offers HDMI directly on the back plane of the graphics card in addition to DVI.
| Test Systems | Page:: ( 4 / 17 ) |
System Setup
Intel Core 2 Extreme QX6800
EVGA nForce 680i SLI motherboard (for GeForce cards)
ASUS P5E3 Deluxe (for Radeon cards)
2GB Corsair TWIN2X2048-6400C4
ATI Radeon HD 3870 512MB
ATI Radeon HD 3850 256MB
ATI Radeon HD 2600 XT
ATI Radeon X1950 Pro
ATI Radeon HD 2900 XT 512MB
ATI Radeon HD 2900 GT 256MB
PowerColor Radeon HD 2900 Pro 512MB
Catalyst 7.10 Press sample
NVIDIA GeForce 8800 GTX
NVIDIA GeForce 8800 GTS 640MB
NVIDIA GeForce 8800 GTX
NVIDIA GeForce 8600 GTS
XFX GeForce 8800 GT Alpha Dog Edition
ForceWare 169.04
300GB Western Digital Caviar SE
Windows Vista 64-bit
Benchmarks
Company of Heroes 1.71 (running DX9)
F.E.A.R. 1.08
Elder Scrolls IV: Oblivion
Call of Duty 4 Demo
Half-Life 2 Episode Two
Lost Planet DX9
World in Conflict DX9
Unreal Tournament 3 Demo
Crysis Demo DX9
| F.E.A.R. Performance | Page:: ( 5 / 17 ) |
| Company Of Heroes DX9 | Page:: ( 6 / 17 ) |
| Oblivion | Page:: ( 7 / 17 ) |
| World In Conflict | Page:: ( 8 / 17 ) |
| HL2 Episode 2 | Page:: ( 9 / 17 ) |
| Unreal Tournament 3 | Page:: ( 10 / 17 ) |
| Lost Planet DX9 | Page:: ( 11 / 17 ) |
| Call Of Duty 4 | Page:: ( 12 / 17 ) |
| BioShock DX9 4xAA/16xAF | Page:: ( 13 / 17 ) |
| Crysis DX9 0xAA/0xAF | Page:: ( 14 / 17 ) |
Crysis – Direct3D
| Crysis DX9 2xAA/8xAF | Page:: ( 15 / 17 ) |
Crysis – Direct3D
| Overclocking and Power Consumption | Page:: ( 16 / 17 ) |
Power Consumption
| Conclusion | Page:: ( 17 / 17 ) |
As you saw in the benchmarks, the Radeon HD 3870 delivers performance that is equal or better than AMD’s flagship Radeon HD 2900 XT GPU in most cases. This is quite an accomplishment considering that the board is equipped with a narrower 256-bit memory interface. Clearly it appears R600 wasn’t taking full advantage of its 512-bit wide interface. We’ve been told that the 3870 pulls even further away from the 2900 XT in DX10 apps, but due to time constraints we weren’t able to test this out. We’ll have a follow-up article testing AMD and NVIDIA’s latest graphics offerings exclusively in DX10 apps in the coming weeks.
You also no doubt noticed that the Radeon HD 3870 wasn’t able to outperform its closest competitor, the GeForce 8800 GT. NVIDIA really hit a homerun with this product and it’s clearly the faster GPU overall, which is why AMD chose to undercut the 8800 GT in price: it may not be faster than the 8800 GT, but some gamers may appreciate its lower price tag. If you’re the type who craves performance though, the GeForce 8800 GT clearly outclasses the Radeon HD 3870 at this point. Radeon HD 3870 also runs considerably quieter than its predecessor, the 2900 XT, and consumes significantly less power. We’ll be curious to see if board partners who elect to employ single-slot coolers on their Radeon HD 3870 cards are able to deliver a card that delivers low noise levels similar to ATI’s reference cooling unit.
The Radeon HD 3850 looks pretty strong right now. As you saw in our benchmarks, it outperformed its closest competitor at the moment, the GeForce 8600 GTS, and delivered a nice performance improvement over the Radeon HD 2600 XT and 2900 GT. In fact in some cases it outperformed the 2900 Pro! However, keep in mind that NVIDIA’s upcoming GeForce 8800 GT 256MB will be competing directly with the Radeon HD 3850 when it launches in a few weeks, so we’ll have to wait and see what kind of performance that board delivers in comparison to the Radeon HD 3850. All indications are it’s going to be a very interesting battle.
The debut of the Radeon HD 3870 and 3850 is quite significant for AMD. They’ve finally delivered competitive parts to go head-to-head with NVIDIA at the performance mainstream segment. It’s been quite awhile since we’ve been able to say this. Both GPUs appear to offer good performance for their segment, while also providing technology leadership with support for DirectX 10.1 and 4-Way CrossFire with CrossFire X. We probably won’t see the first DX10.1 titles until this time next year at the very earliest, but CrossFire X has potential to be very interesting for those of you who prefer to upgrade incrementally. You can buy one RV670 card now, and up to three more boards as your performance needs (and budget) allows. NVIDIA has their own 3-Way SLI solution that will be launching shortly, but this will only be available for their high-end cards, the GeForce 8800 GTX and Ultra. AMD’s providing CrossFire X-compliant cards at much lower price points.