There is possibly a problem with Wattman on the 17.9.1. I unfortunately flashed my BIOS, and then updated the driver, so I'm not sure if it was my BIOS flash or the driver that is holding back. With 17.8.2, my default voltage for the HBM was 1.050V, for 945MHz, but I can get that down to 1000mV for 1100MHz just fine. Anything over 1100MHz just crashes. I think i'll go back to 17.8.2 for the moment, as everything seemed to be working better with that driver. i'll give it a test, at least.