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Noise, Temperature, Overclockability and Compatibility

We measured the level of noise produced by the ATI Radeon HD 3870 X2 with a digital sound-level meter Velleman DVM1326 using A-curve weighing. The level of ambient noise in our lab was 36dBA and the level of noise at a distance of 1 meter from the working testbed with a passively cooled graphics card inside was 43dBA. Here are the results:

The new card features an unusual method of controlling the speed of the cooler’s fan. The speed depends not only on the data from the thermode but also on the load on the command processors. As a result, the fan speed is being varied constantly and in a rather wide range under load, and the level of noise changes accordingly. The card is almost silent in 2D mode. It was hard but we tried to find the peak of noise, too. Most of it is produced by the air flowing through the heatsinks, which is perceived as quiet hiss. It is barely audible in a closed system case and is not irritating at all.

The Radeon HD 3870 X2 has two graphics cores but the appropriate screen of the Catalyst Control Center displays the temperature of the first core only. It varies from 51 to 56°C in idle mode and grows up to 78°C in 3D applications. The temperature of the second core should not differ more than 2-3°C from it. So the cooler copes with its job notwithstanding its simple design. As opposed to the Radeon HD 2900 XT whose power draw is comparable to the new card’s, the developer has managed to find the balance between cooling performance and comfortable noise characteristics thanks to the use of two rather economical GPUs.

We made an attempt to overclock our Radeon HD 3870 X2 using the standard options of the Catalyst Control Center, but it failed completely. The graphics card was not stable even if we increased the GPU frequency from 825 to 850MHz: there was a failure after a while and the driver would enable the restore mode. We left the serial card at that, but we are planning to volt-mod a Radeon HD 3870 X2 in the future to see what it can do at increased GPU and memory voltages.

The ATI Radeon HD 3870 X2 proved to be perfectly compatible with all mainboards we started it on. The card communicates with the bus via a PCI Express switch, and versions 1.1 and 1.0a of this interface have identical speed characteristics. That’s why there should not be any compatibility issues.

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