ATI Radeon HD 3870 and 3850 Hands-On

By: James Yu Posted on November 15, 2007

Why would Nvidia release a card that performs almost as well as its high-end card but charge only half the price? Demand for the GeForce 8800 GTX wasn't on the decline when Nvidia released the GeForce 8800 GT. In fact, GTX chips were still on allocation, and Nvidia didn't have enough chips to fill customer orders. A company doesn't voluntarily give up hundreds of dollars in profits per unit unless there's a very good reason. Maybe Nvidia figured out that it could make more money by reducing prices and selling more chips. Or maybe AMD spooked Nvidia with rumors of a new line of Radeon GPUs that are half the size of the original Radeon HD 2000 GPUs but just as powerful. Judging by AMD's new ATI Radeon HD 3850 and ATI Radeon HD 3870 graphics processors, we're leaning toward the latter.

The new ATI Radeon HD 3870 and 3850 GPUs are based on an updated Radeon HD 2900 XT design. Both GPUs have all the features first introduced in the Radeon HD 2000 series, including DirectX 10 support, integrated HDMI, a hardware tessellation unit, and a 512-bit internal ring bus. The new chips have the same number of stream processors as the Radeon HD 2900 XT, but are only half the size thanks to a smaller 55nm manufacturing process. The manufacturing improvements will let AMD reduce prices considerably from the Radeon HD 2900 XT's current $399 asking price. AMD aims to have the ATI Radeon HD 3870 512MB available in retail at $219 and the ATI Radeon HD 3850 256MB at $179.

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You may have noticed that the new Radeon GPUs don't have the usual Pro, XT, or XTX designations. ATI Radeon models will now use the last two digits of the model number to indicate the GPU variant instead of using the old Pro and XT monikers. If it makes things easier, you can think of the Radeon HD 3870 as the XT and the Radeon HD 3850 as the Pro.

The more powerful Radeon HD 3870 has a dual-slot cooler, whereas the Radeon HD 3850 requires only a single slot. You can combine two Radeon HD 3870 or 3850 cards in a traditional dual-card CrossFire system configuration, but the cards also have support for AMD's upcoming multi-GPU CrossFireX platform that can support two, three, or four video cards. Both cards will require an external six-pin power connector from the system power supply, which will only need to be 400W-500W for a two-card CrossFire setup and considerably less for a single card. Hybrid car drivers and other green-minded individuals will appreciate the Radeon HD 3800 line's new ATI PowerPlay feature, which lets the system adjust GPU clocks, memory clocks, and voltages based on GPU activity. The on-the-fly power management will let cards run cooler and quieter with reduced fan speeds when the GPU isn't running any intense 3D applications.

ATI engineers took the opportunity to add future-anticipating DirectX 10.1 and PCI Express 2.0 support into the new chips. Keep in mind that DirectX 10.1 is only an incremental upgrade, so don't expect many game developers to switch over and make all the current DirectX 10 cards obsolete overnight. Both ATI Radeon HD 3800 GPUs also offer full hardware-acceleration support for H.264 and VC-1 high-definition video decoding, which lets the system move all the decoding work from the CPU to the GPU.

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Radeon HD 3800 GPU performance should be comparable to the Radeon HD 2900 XT, but frame rates will vary due to clock speed, memory speed, and memory interface differences. The Radeon HD 3870 checks in with a 775MHz engine clock, just slightly ahead of the Radeon HD 2900 XT's 740MHz, whereas the Radeon HD 3850 comes in at 670MHz. The Radeon HD 3870 also has faster 2.25GHz memory compared to the 3850's 1.66GHz and the 2900 XT's 1.65GHz memory. AMD is using two memory suppliers, but all chips will be clocked at standard settings. However, some Radeon HD 3870 and 3850 cards may ship with faster 2.4GHz and 1.8GHz memory chips respectively. Card owners can overclock their cards using the ATI OverDrive utility built into the Catalyst drivers. ATI reduced the memory interface in the new chips from 512-bit to 256-bit, which could be considered a step backward. However, ATI claims that bandwidth demands haven't increased as expected because developers are learning to use compressed textures more often thanks to the console development environment.

	Radeon HD 2900 XT	Radeon HD 3870	Radeon HD 3850
Die Size	408mm2	192mm2	192mm2
Manufacturing Process	80nm	55nm	55nm
Stream Processors	320	320	320
Clock Speed	740MHz	775MHz	670MHz
Memory	512MB	512MB	256MB
Memory Speed	1.65GHz	2.25GHz	1.66GHz
Memory Interface	512-bit	256-bit	256-bit
PCI Express	PCI Express x16	PCI Express 2.0 x16	PCI Express 2.0 x16
DirectX	DirectX 10	DirectX 10.1	DirectX 10.1

PC enthusiasts looking for a GeForce 8800 GTX killer will have to wait until January 2008 when the Radeon HD 3870 X2 takes over as AMD's flagship video card. As the X2 label implies, the new Radeon will have two GPUs on a single card.

System Setup: Intel Core 2 X6800, Intel 975XBX2, 2GB Corsair XMS Memory (1GBx2), 160GB Seagate 7200.7 SATA Hard Disk Drive, Windows XP Professional SP2. Graphics Cards: Radeon HD 2900 XT 512MB, Radeon HD 3870 512MB, Radeon HD 3850 256MB, GeForce 8800 GT 512MB, GeForce 8600 GTS 256MB, Graphics Drivers: Nvidia Forceware 169.09 beta, ATI Catalyst 7.10, ATI Catalyst 8.43.1 beta

As expected, the ATI Radeon HD 3870 performs almost exactly like a Radeon HD 2900 XT--very impressive considering that the HD 3870 will sell for nearly half the price of the HD 2900 XT. The GeForce 8800 GT wins all the single-card tests with the exception of BioShock. The results shouldn't be surprising because AMD is pricing both new Radeon cards below the GeForce 8800 GT. We only had a single ATI Radeon HD 3870 card, but we did have two ATI Radeon HD 3850 cards for CrossFire. The single Radeon HD 3850 thrashed its GeForce 8600 GTS counterpart in the sub-$200 competition. Our dual Radeon HD 3850 cards performed well in 3DMark06, BioShock, and Company of Heroes, but we could not get the pair to work properly in World in Conflict and Crysis.

The Radeon HD 3870 512MB looks like a winner in the sub-$225 price category. It's slower than the GeForce 8800 GT 512MB, but it's more affordable and offers a similar performance-per-dollar ratio. Expect the battle for the $200 video-card market to get even more intense as Nvidia prepares to release a more affordable 256MB GeForce 8800 GT. The Radeon HD 3850 might be slower than both the Radeon HD 3870 and the GeForce 8800 GT, but you can't argue with the $179 price, and it crushes the GeForce 8600 GTS, its closest competition in the benchmarks.

We expect pricing to be extremely volatile for all the newly announced cards, the GeForce 8800 GT, ATI Radeon HD 3870, and the ATI Radeon HD 3850, through the end of the year. The new products have generated a lot of consumer interest, and actual retail prices may stay above MSRP until there's enough supply to meet customer demand.

The 2007 holiday season will be remembered as the time when graphics-card manufacturers took turns assaulting eager PC enthusiasts with ridiculously low-priced DirectX 10 video cards. They couldn't have come at a better time because we're going to need that extra graphics power to handle heavy-hitters such as The Orange Box, Call of Duty 4, and Crysis. The new ATI Radeon HD 3800 cards will be available in retail stores and online starting November 15.