I have a ROG Strix 1080ti OC.
After 30 minutes or so the GPU ignores the OC set by OCTune and drops back to 1569MHz which is the base clock for this card.
[HWInfo tells me that I'm having Performacing limitation due to Utilization. Which as far as I understand is that the GPU is not recognizing the miner as a heavy GPU user. And clocks it back down.
The only fix I know is to restart the computer or play a video in the background.
I have the latest RC version.