Size, Noise and Heat
The card we were sent to test looks identical in every way to the Radeon HD 7870. The fan is still a radial blower type, which has the advantage of sending hot air out of the casing. The fan doesn't, however, seem to be as well calibrated as on the Radeon HD 7870, making more noise here.
At idle first of all, the fins can be clearly heard when rotating. As always when it comes to computer hardware, not everyone is affected by noise in the same way—some users will find it more annoying than others. The reading was nevertheless 3 dB(A) higher than with the Radeon HD 7970. This is equivalent to a doubling in volume.
In games, the noise level does, of course, go up, but is acceptable for the level of performance you get in return (see below).
Power consumption is a real strength of the AMD Radeon 7000 series and the HD 7850 is no exception. Both in 2D and in games, it's at a similar level to its predecessor, the Radeon HD 6850, with 89 watts at idle and 296 watts in games. Given that the card's performance is also a good bit up on the HD 6850 (see below), this power consumption reading is a good result, offering an improved trade-off between power use and performance.
Better still, the excellent ZeroCore Power feature gives a 16% reduction in energy consumption at idle and allows you to turn the card's fan off. For this, the computer has to be configured so that it switches the screen off after a given period of time. As soon as the screen goes on standby, the card is almost entirely switched off and only consumes 3 watts of power, bringing the overall consumption of our test computer down to 74 watts. This feature will delight those who constantly leave their computer on.
From a technical point of view, the Radeon HD 7850 is a slightly bridled HD 7870. The number of processing units—which can, to simplify things, be compared to the cores on a CPU—is down from 1280 to 1024 and the GPU clock is down from 1 GHz to 860 MHz. The 2 GB of GDDR5 memory is still clocked at 1200 MHz, however, and it still has a 256-bit bus.
Average general performances
Click on the image to see all our readings
and compare graphics cards in the Face-Off
In practice, this translates to a 12% performance drop on the Radeon HD 7870. In comparison to the old generation of cards, the 7850 is on a par with the Radeon HD 6970 and therefore a good way ahead of the Nvidia GeForce GTX 560 Ti.
Once again, AMD has done very well, increasing performance by 44% on the old generation (Radeon HD 6850) while simultaneously maintaining the same level of power use. The only drawback here is the fan on the generic model, which could be a bit quieter at idle.
See the Graphics Card Performance Index Table