After a holiday break, AMD’s staggered launch of the Evergreen family picks back up today with the launch of the Radeon HD 5670. The 5670 marks the desktop launch of Redwood, the 3^rd chip in the Evergreen family, designed to fit in below the Juniper chip that powers the Radeon HD 5700 series.

AMD has been relatively straightforward in designing the Evergreen family. Each chip is half of its bigger brother. This means that the Redwood chip and the 5670 is in most ways half of a Juniper/5770: half the SIMDs (400), half the ROPs (8), half the texture units (20), etc. The core clocks are also slightly changed compared to the 5870 and 5770; here we have a core clock of 775MHz instead of 850MHz as found on those cards. So on paper, the 5670 is going to be slightly less than half of a 5770 in performance.

The one hardware unit that hasn’t been halved is the memory bus – we still have the same 128-bit GDDR5 memory bus as found on the 5770, but here it’s clocked at a 4GHz data rate. So the 5670 has a higher bandwidth-to-compute ratio than the 5770 does.

In nearly chopping Juniper in half, AMD has brought the transistor count down from 1.04B to 627M. Those transistors occupy a space of 104mm2, which is understandably smaller than the 5770, but also smaller than the RV730 GPU that powers the Radeon HD 4670, the card the 5670 replaces. This smaller die brings load power down to 61W, and idle power down to 14W.

While most of the functional units have been halved, the feature set remains otherwise unchanged from the rest of the 5000 series. DirectX 11, UVD2 video decoding, angle-independent anisotropic filtering, HDMI bitstreaming, and supersample anti-aliasing are all accounted for. Eyefinity is also here, using a slightly different port configuration to continue bringing support for 3 monitor Eyefinity.

At $99, the 5670 is intended to stake out the all-important sub-$100 position for video cards, which is a big price point for price-sensitive buyers and OEMs. Bear in mind that the entire sub-$100 market encompassed 2/3rds of all video card sales last quarter, according to AMD and Mercury Research. Given the low transistor count and small die size of the 5670, we expect that AMD will have a lot of price latitude to work with going forward – as 40nm production costs and GDDR5 costs come down, this board should be cheaper to make than the 4670 ever was.

AMD considers the chief competition for this board to be the NVIDIA GeForce GT 240, which we reviewed last week. However this price point also brings AMD in to competition last year’s parts:  the GeForce 9800 GT and Radeon 4850. The former is in good supply, and the latter still available enough at this moment to be a viable alternative. As we’ll see, this is by no means a slam-dunk for AMD today.

Coming from CES, we had a chance to talk to vendors about the 40nm TSMC situation, which has been a thorn in AMD’s side since the launch of the 4770 last year. What we’re hearing is that the situation is improving (which is why 5800 series cards are finally usually in stock) but that it’s still not as good as everyone would like. For this launch there are 50k+ cards, which should be more than enough to satisfy demand. We don’t expect there to be any supply issues with the 5670.