Size, noise and heat generation
Just 21 cm long, the Radeon HD 7770 can be classed as a small card. This cooler on the model sent to the press is an axial type, meaning that not all the hot air is sent out of the box. Here this isn't too much of an issue as the chip doesn’t heat up much.
When it comes to noise, the fan doesn't do that well. At idle, the rotation of the blades can be heard and makes a slightly annoying high-pitched noise. This gets louder in gaming and while we only measured it at 43.5 dB(A), the high pitch remained.
In view of the impressive energy consumption readings for the Radeon HD 7970 and Radeon HD 7950 it’s not surprising to see that the HD 7770 consumes so little. At idle, it draws just 87 Watts, which is 10% down on the old generation (Radeon HD 6790).
During periods of long inactivity (when the screen switches off in fact), Zero Power cuts the fan off and energy consumption drops 10 Watts to 74 Watts. This feature, a very good innovation, is something we detailed in our test of the Radeon HD 7970.
We measured a maximum reading of 256 Watts at the socket during gaming. Once again, this is better than the Radeon HD 6790 which draws 297 Watts under the same conditions. The Nvidia GeForce GTX 550 Ti is far behind at 330 Watts.
At 1 GHz (75 MHz higher than the very high end Radeon HD 7970) the chip is clocked quite high. Nevertheless, the Radeon HD 7770 has far fewer processing units (640 against 2048 on the 7970).
This of course means that this model gives much lower gaming performance. It only does 10% better than the old Radeon HD 6790 and the Radeon HD 6850 is 10% faster. Compared to the Nvidia offering at the time of writing, the HD 7770 is 20% faster than the GeForce GTX 550 Ti, but 40% down on the very popular GeForce GTX 560 Ti.
This sort of performance will allow you to play current games comfortably on a screen with a reduced definition. Gaming on a full-HD screen will require a few compromises when it comes to the game’s graphics options.
Note, the PCI Express 3.0 interface (PCIe 3.0) is included, as is DirectX 11.1 compatibility. Backwards compatibility means that the Radeon HD 7770 functions perfectly on PCIe 2.0 motherboards. What's more, we didn't note any difference between use in PCIe 3.0 and PCIe 2.0 modes.
DirectX 11.1 will only be available on release of Windows 8 (end 2012). Games using this instruction set will therefore also have to wait until then.
At the end of the day the Radeon HD 7770 doesn't offer the same gain over the previous generation as the cards higher up the 7000 range. It will nevertheless give a decent showing on screens with low definition or if you’re prepared to lower resource hungry effects in the highest load games. The asking price (around £130 on launch) is perhaps the only thing that might hold you back: the Radeon HD 6850 is now available for less and offers significantly better performance!
Consult the performance index table