Power Consumption and Noise
We have a few final data points to cover before bringing this article to a close. Throughout all of our benchmarking, we monitored how much power our NVIDIA based test system was consuming using a power meter, and also took some notes regarding its noise output. Our goal was to give you all an idea as to how much power each configuration used and to explain how loud the configurations were under load. Please keep in mind that we were testing total system power consumption here, not just the power being drawn by the video cards alone.
The GeForce 7950 GX2's power consumption, regardless of whether or not its clocked at NVIDIA's or XFX's specifications, falls somewhere in between a single GeForce 7900 GTX and a 7900 GTX SLI configuration. While idling at the Windows desktop the GX2 system peaked at 195w, and while running with a full 3D workload it peaked at 332w, 44w lower than a pair of 7900 GTX running in SLI mode.
While we were testing the new GX2, we also positioned a sound level meter a few inches away from the card to see how much noise it's dual coolers were generating. In the worst case scenario, with the fans on both coolers running at full speed and the meter placed directly above the heatsinks, the GX2 registered 68db. If we backed away a few more inches though, the sound of the CPU cooler and PSU drowned out the GX2. Subjectively speaking, we would not consider the GX2 loud by any means. The fans emit more of a whine than a 7900 GTX, but we weren't distracted by the sound at any point in our testing.
Having a pair of PCBs sandwiched together, however, does make the 7950 run a but on the warm side. We sampled temperatures using an infrared thermometer at various points on the GX2 and found that the heatsink surface on the front GPU hit 49oC, while the other heatsink in the middle of the PCBs was at 62oC at the same time. We also took a reading from the back of the PCB behind the GPU and found that the board hit a peak temperature of 67oC. That's a huge difference in temperature between the front and middle-mounted heatsinks. This situation could pose a problem in a case that's not well ventilated.