Well, as an update to all this - I put it all together, and everything works great!
System with everything running stock worked perfectly. The x99 Taichi already seemed to have the latest bios, and the 128GB RAM worked out of the box.
I tried loading the XMP profile for 3000MHz, 1.35V, 125 BLCK, and 14-14-14-34 timings... and well, it didn't get far, as expected
I've since settled on a conservative middle-ground - 2666MHz, 1.2V, 100 BCLK, and the same 14-14-14-34 timings, and it seems to be rock-solid so far.
The 5960x handles being run at 4.2GHz with 1.15V core, which seems like a respectable enough middle-ground overclock. Not sure I particularly want to push it any further... kicks out too much heat for my case to successfully exhaust
I'm doing similar VFX with sims etc. I already have 5960x and was considering upgrading my cpu to another that could address 128gb. Now after reading your post I'm having a change of heart. I was wondering if you can confirm that the machine is actually addressing all 128gb?
Hey, sorry, I never dropped back to check this thread. In case it's still useful information to anyone, I can confirm that yes, I've definitely made use of greater than 64GB of the RAM pool in a single session, and it works fine. For the avoidance of doubt - I typically entirely disable the Windows page file, so if something runs out of available physical ram, it simply crashes. (I tend to prefer that state to having the computer descend into a grind for half an hour... much better to have the program crash and then spend half an hour reducing the RAM footprint of whatever I'm working on