Please note that our "under load" tests aren't conducted in an absolute peak scenario. Instead, we have the cards running a real game, Crysis 3, in order to show us power draw with a more typical workload.
Here's where the GM206's smaller size and narrower memory interface pays positive dividends: power consumption. Our test rig's power use at the wall socket with an Asus Strix GTX 960 installed is 78W lower than with a Radeon R9 285 in the same slot. As you've seen, the two cards perform pretty much equivalently, so we're looking at a major deficit in power efficiency.
Noise levels and GPU temperatures
These new video card coolers are so good, they're causing us testing problems. You see, the noise floor in Damage Labs is about 35-36 dBA. It varies depending on things I can't quite pinpoint, but one notable contributor is the noise produced by the lone cooling fan always spinning on our test rig, the 120-mm fan on the CPU cooler. Anyhow, what you need to know is that any of the noise results that range below 36 dBA are running into the limits of what we can test accurately. Don't make too much of differences below that level.
Yeah, these big coolers are pretty much overkill for the GTX 960 at stock clocks. The smallest one of them all, on the Asus Strix GTX 960, is quiet enough under load to hit our noise floor—we're talking whisper quiet here—while keeping the GPU at 60°C. Jeez.
The one bit of good news for the AMD camp is just how very much these coolers are overkill for the likes of the GTX 960. MSI uses essentially the same Twin Frozr cooler on its R9 285, and that card also reaches our noise floor while drawing substantially more power and turning it into heat.