I suspect it's more a case of the task can't be broken down in to any smaller chunks. Everything has it's limits. An example might be encoding a video on 1 CPU taking 80% load or a 10% load on 8 CPU's. But still only 10% on 8 CPU's when 10 CPU's are available because the task can't be broken down into enough threads to use all 10 CPU's.

@dbmix has 80 CPU's and he want them to all run at 100%!?!? Assuming 3DMax supports all 80 CPU's there's no reason to think it's going to max them all out when rendering. Sure it might max out 8 CPU's but when the same job is split over 64 CPU's and doesn't even touch 18 CPU's let alone top 50% on the ones it is using, he is panicking.

@dbmix, do you have a lot of 3D tasks to render? (I assume it's your main business given the beast of a server). Maybe running 3-4 copies of the program in parallel and getting them to run separate tasks would be the best use of the available resources?