Low GPU usage.

[Icathian]

My PC:

i5 3570k @ 4.5ghz
gtx 970
16gb ram ddr3 1600
ssd 128gb
PSU 850w

Usually I can run wow @ ultra settings no problem, but for some reason if I try to suddenly look at a distance, or I get too close to a bonfire or people start to cast a lot of spells around me, my fps immediately drops to 30-40fps for no reason. I've discovered that in these moments, my gpu usage falls back to 30-35%

I've found that if I open Task Manager and set wow64.exe process to Realtime, gpu usage go back to being 80-85% and the problem is fixed, at least until I have to open wow again.

It's very annoying, any potential fixes would be most appreciated.

[Blackmist]

Turn off Vsync? If that fixes it but you can't cope with the tearing, you might want to look at a monitor with a higher sync rate or even one with G-sync.

[Lathais]

This is normal WoW. Not much you can do about it. WoW bottlenecks even the most powerful CPUs in the situations you describe. As soon as you look way in the distance or a lot of spells start going off at once, the CPU bogs down with all the draw calls. They are all in one primary thread which must be processed in a specific order. Therefore, the CPU bottlenecks. The GPU usage goes down because it is waiting on info from the CPU. Again, this is very normal for WoW even with top end systems. The only thing you can really do is OC your CPU and deal with the FPS drops in those situations.