Here is a little test, by Linus Tech Tips, of the dual-GPU Radeon HD 6990 stressed by FurMark 1.9.0.
There is an odd thing with video: it looks like both GPUs of the HD 6990 are loaded by FurMark in… windowed mode. CrossFire on gaming cards works only in fullscreen mode (see HERE). So why both GPUs are stressed in windowed mode?
GPU temperatures: 82°C for one GPU and 87°C for the second one. I don’t know why but I’m nearly sure that in fullscreen mode, the temperatures can reach 90°C and more…
As you can see on the video, there is a little lighting problem with FurMark 1.9.0 and Radeon cards: the furry torus is not lit properly (reversed). During the dev of FurMark 1.9.0 I never noticed this bug (maybe a change in recent Catalyst…). It doesn’t matter, I will check it and fix it for the next update of FurMark.