Last week tech magazines noticed that the Radeon R9 290 series was making low level operational changes that will have a direct impact on the power, noise, and performance of the cards.
It would appear that fans were running too slow, which could have resulted in lower performing cards.
The new catalyst update fixes a problem with the variability in the fan speeds on the cards. Specifically AMD has changed the algorithms for how their drivers handle the fan speeds and overridden the BIOS defaults.
Currently fan speeds are based on percentages, but now it seems that AMD has switched to controlling fan speeds on an absolute basis, using the measured RPM of the fan.
For the release of the new driver, AMD said that it had identified that there's variability in fan speeds across AMD R9 290 series boards. This variability in fan speed translates into variability of the cooling capacity of the fan-sink.
Using PowerTune technology this could be corrected this variability in a driver update and will normalise the fan RPMs to the correct values.