As Nvidia continues its long-rumored expansion of its DirectX 10 GPU lineup into the budget videocard territory, the most significant feature of these new parts is the one detail that Nvidia managed to keep secret: a new video-processing engine that renders these parts more powerful in terms of HD-video decoding than even the mighty 8800 GTX.

Nvidia claims this next-generation PureVideo HD engine renders the GPU capable of offloading all H.264 video-decode chores from the CPU, enabling even entry-level PCs to play Blu-ray and HD DVD content without chugging. The new GeForce 8600 GTS is also the first GPU to support dual-link HDCP decryption, solving a big problem with displaying high-definition video on 30-inch panels; this feature is optional on the 8600 GT (it's left up to the OEM to implement). HDMI support is optional on both cards. (here again, it's up to the OEM to implement).

In order to bring DX 10 capabilities down to the $200 to $250 price range, Nvidia has drastically reduced the number of stream processors in the 8600 GTS (available now) and the even less-expensive 8600 GT (which will sell for $140 to $160 when it arrives at retail May 1): These chips each have just 32 floating-point units, compared to the 8800 GTS's 96 and the 8800 GTX's 128. Both new GPUs are manufactured using an 80nm fabrication process, and each has 289 million transistors. Clock speeds differentiate the 8600 GT from the 8600 GTS, with stock core clock speeds of 540- and 675MHz, respectively. Both cards have 256MB of GDDR3 memory running at 700MHz and 1GHz, respectively. These GPUs have rather narrow 128-bit memory interfaces compared to the 256-bit interfaces on the 8800-series.

Of course, you can expect the third-party OEMs who actually build retail product based on these GPUs to push the envelope in terms of clock speeds, as Asus has done with the EN8600 GTS Top reviewed here. The GPU on this card is clocked at 745MHz and its memory runs at 1.145GHz.

Asus' card delivered very respectable performance for the price, with a single card serving up the punishing Shader Model 3.0 tests 3DMark06 Game 1 and Game 2 at 7.3 and 8.7fps, respectively. More importantly, the card proved able to render Quake 4 playable at 1920x1200 widescreen resolution, delivering the game at 41.2fps. It had a tougher time with FEAR at that high resolution, scoring an average frame rate of just 25fps. We're thinking of adding Chris Taylor's new RTS Supreme Commander to our benchmark lineup, but you probably won't want to play it on an 8600 GTS—at least not at 1920x1200—because it was only able to play that resource-intensive game at 18.7fps.

The situation improved when we dropped an identical Asus card in for SLI benchmarking. Quake 4 jumped up to a very playable 75.6fps, while our FEAR and Supreme Commander scores also nearly doubled, to 43 and 32.4fps, respectively.

Nvidia also announced an even less-expensive DX 10 GPU, the GeForce 8500 GT, which will sell for between $80 and $100. When you step down this low, however, you'll get just 16 stream processors and even lower clock speeds than the 8600 GT, with a core running at just 450MHz. Oddly enough, Nvidia's partners will be able to offer the board with either 256- or 512MB of DDR2 memory running at 900MHz (with the same 128-bit memory interface). But if you're looking for a powerful HD video decoder, this part will have the same engine as its more costly cousins.