Hello, I don't know how to file a bug report.
I got the latest Crimson driver 11.15 and the Global Overdrive settings are broken.
In particular the speed setting for the memory is bugged. I can set the memory speed to something lower than the 1500 MHz, but it will be stuck at the new setting - the setting is not the maximum allowance (as it was in the last driver), but it's fixed at that speed.
Of course, this leads to higher temperatures.
Also, once you initially set a value for memory speed you can't go below that later on. So I first set 1250 MHz, then it was stuck there.
I thought maybe there's a load glitch or something, so I set a new value of 1325 MHz. Now I can't go back to 1250 MHz, even after closing and restarting the control center.
Also the temperature of the card is now stable at a moderately high value (39°C) and the core clock doesn't fall anymore below 500MHz, probably due to the memory clock being fixed.
My graphics card is a Radeon HD 7970, the mainboard Gigabyte with Z77 chipset.