Physics on CPU instead of GPU?

[Shor]

I am using HDT-SMP physics (from HydrogenSays website, for SSE 1.5.53) and am having an issue where after so many minutes / so many cell doors my FPS goes a bit batty - the FPS reported is a constant up-and-down blur. of numbers.  (I am using FRAPS) If I save and restart it goes back to constant near-60 (where it is clamped AND vsynced in the INI's.)  My GPU is a NVidia 1080 ti.  (My CPU is an i7 8700K mildly OC'd to 4.9 GHZ)

 

When I look at the performance on Skyrim Perf. Monitor, (run through MO2) the GPU performance is all over the place.  The GPU graph looks like a seismograph.  Always.  The other graphs are all pretty stable, with the VRAM  never going above 6GB  Note:  The GPU temps never go above 85c.  Note also that the CPU never goes much above 35%  (Of course, the SSE Perfmon leaves a LOT to be desired...)

 

Now, my thought is that somehow the implementation of opencl on NVidia is not so good...  To this end I have D / L'edd the latest opencl implementation for Intel CPU w / o GPU.

 

My questions are twofold:  1, does anyone have any better thoughts as to why my system is going nuts after a while?  And, secondly - If I go the CPU route, how do I disable the openCL implementation on my GPU?