Power Consumption & Temperatures
Unlike the Radeon HD 4850 we tested a few weeks ago, the Visiontek Radeon HD 4870 proved to be quite power hungry, sucking down an incredible 193 watts at idle (this is the overall system power consumption). As a result the Radeon HD 4870 consumption is considerably higher than even the GeForce GTX 280 graphics card.
Under load the Visiontek Radeon HD 4870 posts more decent numbers, using considerably less power than the GeForce GTX 280 and GTX 260 cards, 9800 GX2, and Radeon HD 3870 X2.
The operating temperatures of the Visiontek Radeon HD 4870 were horrible, with idle temperatures never dropping below 74 degrees. The large 80mm blower fan was able to keep the stress temp at 82 degrees, though this was still too high in our opinion.
Although we never experienced any kind of problem due to the high temperatures, it's relevant to note that the slower Radeon HD 4850 card is even hotter. This can be explained by the 4850's single slot heatsink design versus the 4870's dual slot cooler.
We experimented further by installing an Arctic-Cooling S1 on the Visiontek Radeon HD 4870 and were able to reduce load temperatures to 49 degrees, while the idle temp was a much more acceptable 33 degrees. In other words, it's not a bad idea to couple these newer Radeons with some after-market coolers if you want to keep a cool case.