Unigine heaven not using 100% of GPU

Hi there guys so I am pretty much a noob to all of this overclocking and benchmarking and recently I have been noticing lag spikes in games such as Arma 3 that weren't there before, round about the time I had to move my PC into an enclosure and reroute all of the fans for optimal airflow. I have tried a lot of different things, my CPU is overclocked but it even happens when I revert the OC.

I have just looked in UNIGINE and it seems that when I run MSI afterburner (tried with GPU OC and default) it shows my GPU is only using 60-70% capacity.

Does anyone have any ideas why this is please?

What settings in game? Which Unigine? What settings on it?
Make sure to include resolution.

Are you sure you are looking at GPU use and not power limit?