AMD has introduced its latest 4000-series graphics chips, two weeks after the last lot. And there's another one coming next month.

Today's launch centre on the ATI Radeon HD 4550 is a mid-range part that packs in 80 unified shaders. The core's clocked at 600MHz, the 512MB of GDDR 3 memory it connects to at an effective 1.8GHz. It fits onto a compact, single-slot card.

Sapphire's Radeon HD 4550: first out of the block

The 4550's lesser sibling, the 4350, is essentially the same chip - the shader count and core clock frequency are identical - but it's hooked up to DDR 2 memory rather than GDDR 3. The memory runs at an effective 800MHz.

Both parts incorporate AMD's UVD 2.0 video processing core and support DirectX 10.1 gaming. They have Powerplay power management on board, and can be connected up to external displays over HDMI, with 7.1-channel audio fed down the pipe as well as video.

Next month's launch will be the high-end Radeon HD 4830, which will pack in eight times as many unified shaders as these two: 640 in all, leaked roadmap slides reveal. It too will support GDDR 3 memory and HDMI with 7.1 sound.

The 4830 is expected to be released on 21 October in the sub-$150 price bracket. There's no word yet on 4550 and 4350 pricing, but they're going to be a lot less than the 4830.

AMD introduced the 320-shader 4650 and 4670 two weeks ago.

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