Roughly two weeks ago, NVIDIA dropped a bombshell with its new G92 based graphics card, the GeForce 8800 GT 512MB. Like most review sites, we were quite taken aback by the extremely competitive price and performance of the new card. And this positive impression was based solely on performance benchmarks, before considering the additional PureVideo HD hardware integrated in the new core that is a significant improvement over the original GeForce 8800 series.
With a single stroke, NVIDIA effectively stole the thunder from ATI's anticipated attempt to revive its faltering Radeon HD 2000 series. Since then, enthusiasts have been buzzing about the GeForce 8800 GT and from all accounts, initial batches of GeForce 8800 GT have been practically sold out. The question of course, is whether ATI's new Radeon HD 3800 series can actually be a solid alternative to NVIDIA's offering. Today is the day we find out, though as circumstances would have it, we received the lesser version of the two new Radeon HD 3800 cards launched, the Radeon HD 3850 instead of the HD 3870.
So what's different about the Radeon HD 3800 series? For one, ATI leads the industry with the first GPU to be manufactured using a 55nm process. As most of you should know, that means a die shrink from the 80nm of the R600 with all the beneficial side effects, like lower power consumption, lower operating temperatures and along with it, greater allowance for higher clock speeds and to enthusiasts - overclocking. With NVIDIA's G92 still on 65nm, ATI has the advantage, on paper at least. But what's really inside this new core, codenamed RV670?
For starters, the RV670 aims to be gunning to be as future proof as you can get for a product in the fast pace of consumer graphics industry. Not only does it match the GeForce 8800 GT in having PCIe version 2.0 support, it is also the first DirectX 10.1 compatible GPU and also the first to use Shader Model 4.1. Now all this is certainly very nice sounding, but with DirectX 10.1 only available with Windows Vista's Service Pack 1 next year, the advantages of DirectX 10.1 mentioned by ATI, like having real time global illumination and compulsory 4x multi-sample anti-aliasing (thereby raising the bar on image quality), may not actually be implemented in 3D games till much later. Also, Microsoft has commented that DirectX 10.1 is really just a minor superset of DirectX 10, similar to the DirectX 9.x updates, which as we know have gone from 9.0 to 9.0c, including the ongoing bi-monthly updates. As far as Microsoft has admitted, all DirectX 10 hardware will work in compliance with DirectX 10.1. The Radeon HD 3800 series may be the first GPU core to officially claim full support, but whether or not it will overshadow current DirectX 10 hardware still remains to be seen because DirectX 10.1 just isn’t out yet.
As for the actual processing hardware, the architecture is similar to the R600, with the exact number of stream processors and texture units but an important distinction is the 256-bit memory bus of the Radeon HD 3800, which probably explained why the RV670 clocks in with 666 million transistors instead of the 700 million on the R600.
For consumers, the immediate advantage of the Radeon HD 3800 series over the older Radeon HD 2900 XT probably lies in ATI's inclusion of its Unified Video Decoder (UVD). If you can recall, this hardware that takes over the task of decoding H.264 and VC-1 video codecs is found only in the mid and lower Radeon HD 2400 and 2600 series, but not on the high-end Radeon HD 2900 XT. In short, this move is similar to NVIDIA adding its VP2 processor to the GeForce 8800 GT.
The other major improvement is the addition of ATI's PowerPlay technology to the Radeon HD 3800 series. This technology had been found previously in ATI's Mobility chipsets and as one might deduce, it's a form of speed throttling similar in concept to Intel's SpeedStep. In this case, the RV670 core and memory clocks will change dynamically according to GPU utilization. So with PowerPlay, while checking your emails for example, you can expect your GPU to change to a lower usage state and draw less power and the reverse to be true when you're running intensive 3D applications. Whether that translates to a sizable or merely minor improvement in power consumption figures remains to be seen but at the very least, ATI claims that the Radeon HD 3870 will have a maximum power draw of 105W and the Radeon HD 3850, 95W. This is almost half the 215W the Radeon HD 2900 XT consumes, though still more than the 45W rating for the Radeon HD 2600 series.
Finally, while details are still scant at the moment, the new Radeon HD 3800 cards will support ATI's CrossFireX initiative, which seems to be a quad GPU configuration to counter NVIDIA's quad SLI. To be available on the upcoming Spider (AMD’s codename for their new all-AMD ecosystem consisting of the Phenom CPU, 7-series chipset and Radeon HD 3800 GPU) platform, such a setup can have up to four Radeon HD 3800 cards supporting up to eight display outputs. On a similar note, ATI also plans to have a dual GPU Radeon HD 3870 X2 graphics product (think GeForce 7950 GX2) out next year, but we'll get to that when it's available.
As for now, the following table shows how the two new Radeon HD 3800 cards compare against the older R600 and since we only have the Radeon HD 3850 in our hands at the moment, we have compared it against some of its likely competitors in terms of pricing. Obviously, prices for some of these existing cards will probably see some adjustments due to the expected US$150 - 250 price range that ATI intends for the Radeon HD 3800 series.
|Model||ATI Radeon HD 3850 256MB||ATI Radeon HD 3870 512MB||ATI Radeon HD 2900 XT 512MB||NVIDIA GeForce 8600 GTS 256MB||ATI Radeon HD 2600 XT 256MB GDDR4|
|Transistor Count||666 million||666 million||700 million||289 million||390 million|
|Stream Processors||64 Shader Processors (consisting of 320 Stream Processing Units)||64 Shader Processors (consisting of 320 Stream Processing Units)||64 Shader Processors (consisting of 320 Stream Processing Units)||32 Stream Processors||24 Shader Processors (consisting of 120 Stream Processing Units)|
|Stream Processor Clock||670MHz||775MHz||740MHz||1450MHz||800MHz|
|Texture Mapping Units (TMU) or Texture Filtering (TF) units||16||16||16||16||8|
|Raster Operator units (ROP)||16||16||16||8||4|
|Memory Clock||1660MHz DDR3||2250MHz DDR4||1650Hz DDR3||2000MHz DDR3||2200MHz DDR4|
|DDR Memory Bus||256-bit||256-bit||512-bit||128-bit||128-bit|
|Ring Bus Memory Controller||512-bit||512-bit||1024-bit||NIL||NIL|
|PCI Express Interface||PCIe ver 2.0 x16||PCIe ver 2.0 x16||x16||x16||x16|
|Molex Power Connectors||Yes||Yes||Yes (dual)||Yes||Yes|
|Multi GPU Technology||Yes (CrossFireX)||Yes (CrossFireX)||Yes (CrossFire)||Yes (SLI)||Yes (CrossFire)|
|DVI Output Support||2 x Dual-Link||2 x Dual-Link||2 x Dual-Link||2 x Dual-Link||2 x Dual-Link|
|Street Price||From US$150||~US$240||~US$329||~US$149 - 169||~US$139|