he Radeon HD 4770 may sound like yet another mid-range graphics card, but there's something special about this one: it's the first consumer card to use a 40nm GPU, namely ATI's new RV740.
Effectively, the HD 4770 is a little sibling to the HD 4870. Its core is smaller, thanks to the new fabrication process, it's been pared back to 640 shaders (as opposed to the 800 of ATI's flagship cards), and the RAM bus has been halved to 128 bits. It does, however, keep the HD 4870's 750MHz core clock and 512MB GDDR5 frame buffer.
In our Core i7-920 test rig, the HD 4770 averaged a playable 33fps in Crysis at 1600 x 1200 with high detail. Even in the challenging high-resolution Call of Juarez test it scored 30fps. Naturally, these scores don't compete with the HD 4870, which scored 42fps and 40fps in the same tests. But, interestingly, these results are identical to those of the HD 4850.
So what differentiates the HD 4770 from that card? Well, for one thing, its smaller, simpler GPU consumes less power - during our tests, total system power consumption peaked at 164W, compared to 175W with the 4850.
But, more significantly, it's also cheaper to make. While the HD 4850 retails for around $190, the HD 4770 is already selling for significantly less. At the time of writing, we were able to find cards available for $150 - around 20% less.
That effectively makes the HD 4850 obsolete, and undercuts Nvidia's GeForce GTS 250 as well - a card it matches on performance. Crysis frame rates were the same with both cards, but the GeForce's Call of Juarez score was lower at 24fps.
We suspect the RV740 has more to give. The move to 40nm gives ATI new scope to drop prices and raise speeds in the near future. So it might make sense to wait a while before investing.
The Radeon HD 4770 exceeds the HD 4850's impressive price/performance proposition while undercutting its power demands. For that reason it takes over as our current favourite mid-range card
