my GPU usage (and thus hashrate) has always fluctuated like a small sine wave from 99% - 90% , after this patch, they all stay a straight line 99% , so that's way more than a 3% increase in hashrate for me.
What's weird, mine went from 90%-96% to 96% straight but the added performance adds 1.5C to the temperature, I might have to clock down a bit to get tot he previous 90C stable line, which means I am forfeiting the benefits of the above optimization. At least I use less energy, the Earth will thank us all...Same here, actually. I was ok with 6870 overclocked to 1000 MHz, but after the change it became unstable so I had to go down to 975, which is kinda sad. Yet, I blame it on poor ventilation in my case, so may be I'll get it running at 1000 again, eventually
That means your 1000 MHz core wasn't actually stable to begin with, but you were getting by because it wasn't being used fully. After the patch it's getting fully loaded which puts more stress on it; Because of that, at 975 MHz with the new patch you might still be getting a higher overall hashrate than before the patch at 1000 MHz