As expected, AMD today officially announced worldwide availability of the Radeon HD 7950 graphics card for desktops. The card is based on the Pro derivative of the 28nm 'Tahiti' core that debuted with the HD 7970 just a few weeks ago as part of the "Southern Islands" range and arrives as a slightly cut-down more affordable alternative to the latter, bearing less stream processors less as well as a lower GPU clock and memory.

Specifically, the Radeon HD 7950 comes equipped with 28 Compute Units, each playing host to four Vector Units containing 16 stream processors apiece for a total of 1792 -- versus 32 CU and 2048 SP on the HD 7970. The card's core clock runs at 800MHz, down from 925MHz on its higher-end sibling, while its 3GB of GDDR5 memory runs at 1,250MHz (5GHz QDDR) but maintains the same same 384-bit memory interface.

So far the reviews have been mostly positive for the Radeon HD 7950, which matches or outclasses Nvidia's single-GPU flagship, the GeForce GTX 580, in most modern games. It also runs cooler and is much more power friendlier than its Nvidia counterpart while still undercutting it by a few dollars at $450. Currently, the cheapest GeForce GTX 580 on Newegg.com is offered by PNY and goes for $470.

A number of more affordable HD 7xx0 cards will be coming later in the first quarter of this year.

According to a recently leaked roadmap, HD 7750 and HD 7770 cards will be available on February 15, reportedly priced at $139 and $149 respectively. They are said to come with 1GB of GDDR5 memory, a 900MHz core frequency, and 832/896 stream processors as well as 52/56 texture units each.

This will be followed in March with the release of performance HD 7850 and HD 7870 GPUs, both featuring 2GB of RAM as well as 1280 and 1408 stream processors respectively. These cards will purportedly occupy the attractive $200-$300 price slot at $249 for the 7850 and $299 for the 7870.