Issues with Mining on 1070 Ti

Hey I am hoping someone has the magic touch here. I have started mining on my GTX 1070 Ti, I'm using nbminer at the moment. My MSI Afterburner settings are PL80%, cclock +100MHz, mclock +500 MHz.

My issue is after about 30 minutes to an hour of mining, my hashrate will drastically drop from around 16 Mh/s to about 10 M/hs. This will then further drop as time goes on until it eventually bottoms out to about 2 Mh/s. After a reboot and re-running the miner then I am back at my 16MH/s.

I have tried looking around to see what could be causing this and I have found nobody with a similar to issue to mine, would anyone have a clue to why this is happening to me?