|Diamond Viper ATI Radeon HD 3870 512MB Video Card|
|Reviews - Featured Reviews: Video Cards|
|Written by Ronald Tibbetts|
|Tuesday, 11 March 2008|
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Diamond HD 3870 Technology
Built on the new R670 core the HD3800 series GPU comes in at an industry leading ultra slim 55nm packing with 666 million transistors under the hood. What does this smaller die size means for us? Well perhaps most importantly is price. With their smaller die ATI can produce more GPUs per batch in comparison to their older R600 core (80nm). How could a simple physical reduction in size affect price? Imagine if you will a tray of brownies, if you cut each individual brownie to a smaller size you get a higher yield per tray. This simple higher yield principal ensures more usable chips, which in turn helps to reduce overall cost, thus bringing the HD3800 series down to the current bargain basement price point we have recently been enjoying.
In addition to a lowered price point the physical die shrink also allows for the individual transistors to be packed into a tighter area, 666 million transistors on 192mm2 for RV670 versus 700 million on 408mm2 for R600. I'll use a brownie analogy again: Imagine the same brownies as before only this time with chocolate chips, now we're going to cut them small again while keeping the same amount of chocolate chips as the larger ones. This engineering feat greatly reduces the electrical impedance of the transistors by shortening the electrical pathways, and allows for the dramatic decrease in power consumption and heat output for the HD3870 (105W peak), to roughly half that of HD2600XT (215W).
With the die shrink ATI/AMD have also borrowed a trick from their Mobility line of Radeons to aid with power draw on the HD3800 series, dubbed PowerPlay. This new built in feature (PowerPlay) dynamically controls the operating frequency and power state of the RV670 GPU, with the ability to seamlessly power down parts of the core when not in use, even during gameplay. These power saving features coupled with a smaller die size will hopefully lead the trend in video processing to more efficient computing as we have recently seen with the CPU.
Included on the RV670 GPU, and now fully functional on all HD3800 series video cards, is ATI's Unified Video Decoder or UVD. UVD is the proprietary video decoding unit from ATI that supports hardware assisted decoding of H.264 and VC-1 video codec standards needed for playback of Blu-ray and HD-DVD media. UVD frees up processor time that would otherwise be spent on software decoding, thus making the HD3800 series with its UVD and low power draw a very attractive solution for home theater PCs builds.
The HD3800 series release also marks the launch of the PCIe 2.0 standard. PCIe 2.0 essentially doubles the bus standard's bandwidth from 2.5 Gbit/s to 5 Gbit/s, meaning a PCIe 2.0 supported connector can now transfer data at up to 16 GB/s both to and from the video card, eliminating any potential bottleneck for years to come. PCIe 2.0 video cards and motherboards are also backward compatible with all PCIe 1.1 devices and most PCIe 1.0 hardware. With the greater bandwidth allowed by PCIe 2.0, ATI/AMD has introduced with the HD3800 series their new multi-video card platform termed "CrossFireX". CrossFireX enabled platforms allow users to link together two, three, and even four video cards on supported hardware.
It should be noted here that the HD3800 series also brings support for the incremental DirectX update to version 10.1. Though hyped by ATI/AMD marketing as a selling feature over the competition, the support for DX 10.1 is completely dependent upon game developers to implement. DX 10.1 adds virtually nothing that developers are likely to care about. The spec revision basically makes a number of things that were optional in DX 10 mandatory under the new standard - such as 32-bit floating point filtering, as opposed to the 16-bit current. 4xAA is also a compulsory standard in 10.1, whereas graphics vendors can pick and choose their anti-aliasing support currently. The spec is likely to be ill-received, as not only does it require brand new hardware, immediately creating a minuscule sub-set of DX 10 owners, but it also requires Vista SP1, and developer implementation. As it stands there is only recent driver support for these hardware features, with ATI Catylist 8.3 released just this month.