The GPU war just got more interesting! For the past few months Nvidia has been having a real tough time fighting back AMD's lower cost as well as equally powerful
offerings leaving them with no option but to cut prices and introduce new products at competitive rates. One such example is the GeForce GTX 250, because the GeForce 9800 GTX+ was unattractive with the cheaper and equally powerful Radeon HD 4850 around. In fact the GTS 250 is nothing but are-branded 9800 GTX+ with extra memory and a much lighter price tag. Hardly a few weeks after that launch, both the Green and Red teams pulled out their new weapons-GTX 275 and HD 4890 and this time Nvidia won. After a month's silence, AMD is out with another weapon.

Features:

The Radeon HD 4770 is the first 40 nm GPU to appear on the scene. It appears
similar to the HD 4830 with 640 stream processors, but its core runs much faster at 750 MHz. In contrast to the 256-bit GDDR3 memory of the HD 4830 and HD 4850, the HD 4770 features GDDR5 memory with half the bus width. For the first time AMD has thrown GDDR5 memory into a mid-range card. Going by the specifications and AM D's naming convention, the HD 4770 fits between the HD 4670 and HD 4830, but the scores will show where it really fits.


AMD has two reference designs for the HD 4770. The first is a regular design with a simple heatsink fan installed on the GPU. The memory chips around the GPU are bare and get cooled by the fan since they are right under the heat sink. The other is the premium design which features a full-length cooler with copper heat pipes and a single L-shaped heatsink for all the memory chips. While some vendors such as XFX offer both options, most will offer only the less expensive regular design to lure buyers.

Performance:

The first retail sample to reach our Test Center was the one sent by XFX featuring the regular design. Our test rig was the Gigabyte GA-MA790FXT¬UD5P fitted with AMD Phenom II X4 955 and 4 G8 DDR3-1333 memory. We started off with 3D Mark Vantage and immediately got a rough idea of how powerful it was-our jaws dropped!
The HD 4770 leaves the HD 4830 way behind and comes close to the HD 4850 and GeForce GTS 250. Look at the game benchmark scores and you will get a clear picture of how powerful the HD 4770 is. Rest assured that you will get playable frame rates at 1680x1050 with AA bumped to 4x depending on the game. Other than Crysis Warhead which kills even the top-end cards at high resolutions, the HD 4770 handled Race Driver: Grid and Left 4 Dead with great ease even at 1920x1200 with 8xAA. Despite fewer stream processors and the 128-bit memory bus width, the HD 4770 lags behind the HD 4850 and GTS 250 by only a few frames per second, which is very commendable. Thanks to the 40 nm process, the HD 4870 consumes 85 Watts less than HD 4850 and 60 Watts less than the GTS 250.



After a brief gaming session, we moved on to find out how far the clocks can be pushed. We enabled ATI Overdrive (OC) from the Catalyst Control Center and revved the GPU and memory clocks to the maximum speeds suggested by the driver. It allowed the GPU and memory to be clocked to 830 MHz and 850 MHz respectively-that's almost an 11 percent increase in core speed and a 6 percent increase in memory speed. With these bumps, the HD 4770 crept very close to the HD 4850 and lagged only 3 to 5 fps behind the GTS 250. We then took it through a second round

of overclocking, but this time using RivaTuner (OC2). After a few trial rounds, we got what we wanted-the GPU running at 880 MHz and memory running at 960 MHz. A good 17 percent jump in core speed and 20 percent jump in memory speed, all thanks to the 40 nm process and GDDR5 memory. This time we were pretty sure it would defeat the HD 4850 and GTS 250, and it did We also got our hands on an HD 4770 with the premium design which was sent to us by AMD. There was no difference in performance, except that the fan got a bit noisy and distracting when the GPU activity was high. Also it heated up more than the regular card because the memory heatsink lacked air cooling. With two HD 4770s in hand we couldn't resist clubbing them in CrossFire. The two red babies zipped past even a HD 4890 and GTX 260. However, they couldn't catch up with the GTX 275.

The power consumption of the HD 4770 deserves a special mention. The overall consumption of the setup was 150 Watts in idle mode and 215 Watts under load. An entry-level 500 Watt power supply would suffice for a gaming rig fitted with an HD 4770-great for mainstream users. The combined power draw of two HD 4770s in CrossFire is less than that of a single GTX 260. With benchmarks running, the temperature didn't shoot beyond 55 degrees C.