ATI Radeon HD 4670 review

It's two months since AMD introduced its HD 4000 series of graphics cards. Until now, the line-up has been a little sparse, with only high-end cards appearing on the market; but that's about to change with the arrival of the Radeon HD 4650 and HD 4670.

The two cards are based on a cut-down version of the RV770 core, known as RV730. The heavyweight original, which powered the HD 4850 and HD 4870, enjoyed 800 stream processors, partnered with 40 texture units and 16 ROPs. The HD 4650 and HD 4670 get just 320 processors each, with 16 texture units and 8 ROPs.

Clock speeds have been tweaked a little too: the HD 4650 has a 600MHz core and a 667MHz RAM bus, while the HD 4670 runs at 750MHz with a 1GHz memory bus.

Unsurprisingly, slashing the number of processors has a big impact on performance. A 512MB HD 4850 averaged 63fps in our 1,280 x 1,024 Crysis benchmark, but when we tested a similarly-equipped HD 4670 card it achieved only around half the performance - averaging 32fps, but sometimes dipping below 20fps. To get a smooth experience we had to drop down to 1,024 x 768, which raised the frame rate to 44fps.

It was a similar story in Call of Juarez: the HD 4850 happily pumped out 42fps on medium settings, while the HD 4670 managed just 25fps.

It's worth remembering, though, that less than a year ago you'd have paid three times as much for this sort of graphical power. And the 4670's scores are slightly higher than those achieved by the Nvidia 9500GT - as is the price. The HD 4670 is expected to make its UK début over the next few days at around £55 exc VAT.

So while the HD 4670 won't be setting any performance records, it's a very tempting proposition for the casual gamer, who doesn't demand top-flight enthusiast settings.

What's more, since it incorporates the same Unified Video Decoder as ATI's high-end cards, you also get dual-stream hardware decoding, contrast enhancement and DVD upscaling. In all, it makes an all-round entertainment PC deliciously affordable.

If you tilt green, rather than red, you'll get similar gaming performance from the Nvidia GeForce 9500GT. But with ten times the stream processors of the GeForce, not to mention twice the frame buffer, the HD 4670 is clearly today's most capable mid-range card.

Author: Darien Graham-Smith