For the past year and a half, the graphics race between AMD and Nvidia has produced more than just red and green smudges on the guardrails of the PC component industry, namely cheaper graphics cards for mainstream gamers. Nvidia’s aggressively priced GeForce 8800 GT is the most recent evidence that, at least in the near term, it’s taken a sharp turn into the midrange lane and stomped on the gas. Judging by last month’s Ge-Force 8800 GT roundup, ATI will need more than just racing stripes and nitrous to defend its price/performance strategy

Under the hood, the ATI Radeon HD 3800 series is little more than a die shrink of the Radeon HD 2000 series with a handful of extra features bolted on. Despite the minor changes, AMD has chosen to dispense with the XTX, XT, and PRO suffixes for naming each product in favor of a more transparent numbering system that denotes the generation, family, and variant. Among the Radeon HD 3800 series GPUs we tested, the HD 3870 and HD 3850 are roughly equivalent to the XT and PRO, respectively.

Last year’s Radeon HD 2900 XT was a 700-million transistor beast on a 408mm2 die, which took some heat from us for, well, being hot under the fansink and requiring two PCI-E power connectors to meet the card’s 215-watt demands. For the 3800 series GPUs, ATI’s engineers took a half-node step from the Radeon HD 2600 and 2400’s 65nm process to deliver double the transistor density (666 million transistors in total) on a 192mm2 chip. The resulting 55nm HD 3800 series graphics cards only require a single 6-pin PCI-E power connector.

The HD 3800 series GPUs are actually based on the HD 2600 and 2400 architecture, evidenced by the fact that they share the 256-bit memory bus (the HD 2900 XT has a 512-bit memory bus) and other R630- and R610-only features. Another power-related improvement you’ll find here is ATI’s PowerPlay Technology, which is a carryover from the Mobility Radeon family. PowerPlay works by dynamically throttling GPU power depending on the 3D load. With the PowerPlay-deficient HD 2900 XT, the average power draw is maxed out regardless of whether you’re playing the system crushing Crysis or an old favorite such as Half-Life 2. The HD 3800 series, however, slashes power draw by as much as 50 and 66%, respectively, when you’re performing general usage tasks or doing some light gaming.

Unlike Nvidia’s latest effort, the HD 3800 series GPUs support Microsoft’s tweaked DX10.1 API, which is scheduled to appear at about the same time as Windows Vista’s SP1 (possibly by the time you read this). DX10.1 brings with it Shader Model 4.1, global illumination effects, better antialiasing performance, and new HDR effects. You won’t see game developers taking advantage of the updated spec for quite some time, and even then, most agree the improvements won’t be revolutionary. Consider DX10.1 as a nice futureproofing add-on. The 2D realm also sees marked improvements over the HD 2900 XT. The HD 3800 series graphics cards are currently the highest-end GPUs from ATI to include ATI Avivo HD dedicated UVD (Unified Video Decoder) hardware designed to handle the H.264, AVC, and VC-1 video decoding of Bluray and HD DVD video, leaving your CPU free to manage other, more appropriate, tasks. As with the rest of the R6xx-based GPUs, the 3800 series have the HDCP-compliant chips and encryption keys, as well as native support for audio and video over HDMI to playback protected HD content.

The 3800 series reaps further benefits from its PCI-E 2.0 support. The spec is capable of delivering up to 16GBps of bandwidth per 16-lane link, which translates to improved gaming performance when the game resources, such as texture and vertex data, overflow to system memory. PCI-E 2.0 also ups the motherboard power output from 75 to 150 watts per slot. With regard to multi-GPUs, ATI hasn’t exactly been asleep at the wheel. Check out the “CrossFire X Factor” sidebar for more details.

The R670 is most likely the final enthusiast product to come out of ATI’s R600 family. Compared to the HD 2900 XT, the HD 3870 has a narrower 256-bit memory bus. The stock HD 3870 comes with a 775MHz core clock (the unit we tested actually clocked in at 777MHz) and 320 stream processors capable of nearly half a teraflop (497 gigaflops) of math processing. This GPU also features a full complement of 16 texture units and 16 render back-ends.

The HD 3870’s frame buffer consists of 512MB of GDDR4 memory clocked at 2.25GHz. Peak board power maxes out at a cool 105 watts. We weren’t able to procure any thirdparty HD 3870s in time for publication, but the units ATI sent us featured a dualslot fansink covered in a Ruby-adorned, transparent red plastic shroud. The fan’s whisper-quiet (for a graphics card) 34dBA rating was barely audible even under the heaviest of loads. The PCB measures just 9 inches long and features a lone 6-pin PCI-E power port. The bracket features two dual link DVI ports and an HDTV-out port. The HD 3870 performed rather well in the benchmarks, breaking 10,000 in 3DMark06 at default settings. Both S.T.A.L.K.E.R. and the DX10-patched Company of Heroes were playable at 1,600 x 1,200, but newer DX10 games such as Crysis and World in Conflict couldn’t manage above 14fps at any resolution. Although Nvidia’s 512MB GeForce 8800 GT outperforms the Radeon HD 3870 in most areas, ATI’s option is a no-brainer for budget-conscious gamers.

Like its more capable sibling, the HD 3850 features a 256-bit memory bus. The card also has 256MB of 830MHz GDDR3 memory, which is capable of up to 52GBps of bandwidth. The HD 3850 also shares the 3870’s 320 stream processors, 16 texture units, and 16 render back-ends. The HD 3850’s core clock is set to 670MHz and can churn out up to 428 gigaflops of mathematic processing.

Unlike the HD 3870, the 3850 is a single slot card. The cooler consists of a red plastic-shrouded fansink, which is rated to produce only 31dBA of fan noise. In our experience, this seemed right on target, even under load. The 9-inch-long slab of PCB is also red and features a single 6-pin PCI-E power connector. At 95W, the peak board power is only slightly lower than that of the HD 3870. The HD 3850’s bracket has a pair of dual-link DVI ports and a port for an HDTV dongle. In 3DMark06, the HD 3850 managed to score just 1,000 points below the HD3870 at each resolution. The HD 3850 really shone in the benchmarks at our lowest benchmarking resolution, 1,280 x 1,024. In S.T.A.L.K.E.R., the card posted an impressive 41fps. The picture with DX10 games was rather less impressive, with only the patched version of Company of Heroes managing to be playable. At less than $180, the HD 3850 is a more than capable card for DX9 and some light DX10 gaming.

The Sapphire Ultimate HD3850 has twice the dedicated memory compared to the stock HD 3850. The other and more obvious difference you’ll notice is that Sapphire replaced the stock fansink with a Sherman tank-sized passive heatsink bristling with heatpipes. The heatsink extends about 1.25 inches above the PCB, and may result in some space problems for gamers with cramped cases. In the benchmarks, the Sapphire Ultimate HD3850 consistently outpaced the stock HD 3850 in 3DMark06. That extra memory was evident in the 1,600 x 1,200 run of 3DMark06, where Sapphire’s card scored more than 200 points better than the stock version. Strangely, though, S.T.A.L.K.E.R. wouldn’t run at the highest resolution. Although the Ultimate HD3850 won’t let you plow through current DX10 titles at higher resolutions, it’s ideal for HDTV enthusiasts who need a silent card, enjoy light gaming, and don’t mind paying a bit of a premium for the privilege.

The only factory-overclocked card we got our hands on was the EAH3850 TOP. Asus stuck with the stock fansink and basic hardware as the reference model. On the surface, Asus’ card has a Company of Heroes: Opposing Fronts shroud decal, but things get really interesting underneath the fansink. Asus bumped the core and memory frequencies to a remarkable 730MHz and 950MHz, respectively. As the tests show, the EAH3850’s higher clocks do a lot more for the card than the Ultimate HD3850’s larger frame buffer.

The Asus card managed to achieve a 3DMark06 score that was less than 100 points shy of the stock HD 3870. Again, though, the card stumbles at higher resolutions, especially in Crysis and World in Conflict. Like the Ultimate HD3850, S.T.A.L.K.E.R. failed to complete the benchmark at the highest resolution. The EAH3850 offers performance almost on par with the HD 3870, but at $20 less. The inclusion of Company of Heroes: Opposing Fronts should seal the deal for gamers who haven’t picked up that gem of an RTS