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ATI Radeon HD 3870/3850: Noise, Overclocking and Power Consumption

We measured the level of noise produced by the reference coolers of the ATI Radeon HD 3870 and HD 3850 cards with a Velleman DVM1326 digital sound-level meter 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. We got the following results:

New ATI Radeon HD 3800 reference cooling systems showed their real best. The top model remained very quite no matter what mode it was operating in, and the younger model stood out just a little bit against the background of other system components only in 3D mode. Maximum graphics processor temperature hit 90ºC and 70-75ºC respectively. As you can see, ATI Radeon HD 3870 warms up quite significantly, however, there is no cause for concern here: the card never lost stability.  Although, if you are not comfortable with this number you can use the latest RivaTuner version and improve the cooling efficiency by increasing the fan rotation speed. However, in this case you will have to put up with higher level of generated noise. Be careful, because extreme lowering of the fan rotation speed may cause the card to overheat and die.

As far as overclocking is concerned, our experiments turned out pretty successful. The maximum frequencies our ATI Radeon HD 3870 was working stably at equaled 850MHz GPU and 1200 (2400) MHz memory.

Despite our expectations, both cards from the new Radeon HD series had no compatibility issues with mainboards that support an earlier version of PCI Express than 1.1. This made it possible to test their power consumption using a special testbed with a modified Intel Desktop Board D925XCV. The measurement was performed with a digital multimeter Velleman DVM850BL (0.5% accuracy).

In 3D mode the cards were loaded by the first SM3.0/HDR test from the 3DMark06 suite running in a loop at 1600x1200 with 4x FSAA and 16x AF. The Peak 2D mode was emulated by means of the 2D Transparent Windows test from PCMark05.


Click to enlarge

The results of our measurements in 3D mode almost ideally coincide with our predictions abut the peak power consumption of both Radeon HD 3800 models. The numbers are normal considering the traditionally hot temper of ATI’s GPUs. It is only with the help of 55nm tech process that AMD managed to keep the power draw of its new GPUs within reasonable limits. By the way, the Nvidia G92 has similar results while having more transistors and 65nm tech process. Note also the economical behavior of the new cards in idle and 2D modes – ATI’s PowerPlay technology seems to do its job well.

Unlike Nvidia’s solutions, ATI’s Radeon HD 3870/3850 load the internal +12V line more than then external one. The load is not higher than 45W even in the hardest mode, which is far below the limit set in the PCI Express 1.0/1.1 specification: 75W for the slot and 75W for each external connector. The +3.3V line has a low load in every mode – 1.6-1.7W.

 
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