Having assaulted the ultra high end (HD5970), high end (HD5870, HD5850) and the mainstream (5750 & 5770) market segments with its new 40nm DX11 architecture HD5**** series of card the firm has now turned their attention to the real bread-and-butter part of the market, namely the value end, hence the Radeon HD5670.

The HD5670 (codename Redwood or to be more precise Redwood XT) is a cut-down version of the HD5770, itself a cut down version of the mighty HD5870. With the HD5670 the transistor count drops below a billion(s) for the first time in the family to 627 million with the cut-down core measuring just 104mm².

The stream processor count is halved from the HD5770 (400 down from 800) with the texture and ROPs also halved as well; 20 and 8 respectively. The shader and core clock run at 775MHz. One thing that hasn’t been touched is the memory interface which remains at 128-bit. At the moment there are two flavours of the HD5670 with 512MB and 1GB of GDDR5 memory, clocked at 1GHz (4GHz effective) which gives a memory bandwidth of 64GB/s, very impressive for a card in this part of the market.

The reference design PCBs use Hynix H5GQ1H24AFR-T0C chips which are rated at 4GHz so there isn’t much headroom for overclocking. The added benefit of the smaller die size is that the card doesn’t need any more power to run other than the 75 Watts supplied by the PCI-E slot, as its maximum wattage is just 61 Watts (14Watts idle). So there’s no extra power connector on the cards PCB, which is handy as the card's single slot design, the first DX11 single slot card, measures 169mm x 110mm x 33mm (WxDxH) meaning that it should be able to fit into smaller systems.

Despite the cut-down nature of the architecture it retains the feature set of the rest of the 5000 series, amongst which are: DirectX 11 support, UVD2 video decoding, HDMI bit streaming and even support for the three-monitor Eyefinity technology.

Surprisingly, how Crossfire is implement is left largely down to the board vendors, in the case of our review boards the reference design had no connectors while the Sapphire board had the usual dual connectors. 

So much for the reference design.

See page 2 for a look at how Sapphire's 1GB version of the HD5670 compares to that from HIS, which sports the standard 512MB of graphics memory.