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Source: www.techtree.comExclusive: XFX HD4770 [Review]
*images.techtree.com/ttimages/story/101505_front.jpg
40nm fabrication is finally commercial and for the first time it's a GPU instead of a CPU, and who other than ATI to bring you the world's first 40nm graphics card.
After striking gold with their 55nm RV770 GPU back in August last year, the RV740 is finally a reality. Shrinking the die further means cheaper cost of production (though the fabrication process itself is more expensive initially at least) since you get more dies per wafer of silicon and also lower power consumption, which eventually gives you lower operating temperatures.
The RV740 is not architecturally very different from the RV770; in fact it supports the exact same features. This GPU is fabricated using the 40nm process and comes with 640 stream processors (or shaders) just like the HD4830. In order to lower the cost of the card, the memory bus has been cut down to 128-bit instead of 256-bit, but to compensate for that ATI has chosen GDDR5 memory which is relatively easy to implement while drawing less power (1.5v). So instead of just shrinking the die of the HD4830, ATI has taken a slightly different route by giving you low voltage and much faster GDDR5 memory coupled with higher clock speeds for better performance.
The HD4830 was never far behind from the HD4850 and now with the HD4770 replacing it and promising better performance, that gap is soon closing up. We managed to snap up the only retail sample of the XFX HD4770 available in the country and are going to compare it with the reference card to find out what XFX has done differently. The direct competition to the HD4770 from Nvidia is the 9800GT, so of course that's there, and then we have the HD4830 and the HD4850 to complete the group.
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*www.techtree.com/India/Reviews/Exclusive_XFX_HD4770_Review/551-101505-537.html
Usually I prefer not to advertise Techtree reviews here, but I thought you might be interested in this one. 8)
will it beat 4850 
