Phoronix installed the new Catalyst 8.8 drivers and tried out the new CrossFire support for Linux:
Back in June we had exclusively shared that CrossFire would be
coming to Linux as part of their Radeon HD 4800 series strategy.
CrossFire (or CrossFire X as it's now known) allows the graphics
rendering workload to be split between multiple Radeon GPUs to deliver
faster performance. Meanwhile, NVIDIA's multi-GPU technology known as
SLI (Scalable Link Interface) has been supported on Linux since
2005. While AMD is still working to address some issues with their
ATI Linux driver, they have been working hard on new features like
CrossFire. How does this feature work though on Linux and does it
deliver similar performance gains to their Windows driver? Today we have
a full rundown on ATI CrossFire for Linux along with benchmarks from the
ATI Radeon HD 4850 and Radeon HD 4870.