In july I had an Nvidia 560. Windows was snappy and fine. Than I bought the MSI R9 380, and after installing the Drivers my HDD slowed down. I don't know why. This hasn't chaged even after CCC 15.7 or 15.7.1. Also, in some games I have worse framerate than the GTX 560. I can't tell wheter it is due the slower HDD or the GPU.
PS: Maybe I have to download the AMD AHCI Driver? (I'm afraid it may slow the hard drive even more)