As far as consumer boards, I've only seen X99 motherboards support this much RAM. These seem to support up to 128GB, and it must be 288-pin DDR4.
I understand server RAM is slower than normal consumer RAM (maybe due to server RAM being ECC?).
This kind of memory requirement could make sense for some machine learning applications. I'm running the Google DeepMind convolutional neural network simulation (http://superintelligence.ch/deepmind/) on my machine right now, and after running for 24 hours, it's already used over 15GB of RAM. I'm only 1/4 of the way through the simulation. My machine has 32GB. I also have a 32GB swap partition on an SSD just in case I need more (which obviously would be much slower than RAM). And I have a dual-GPU Titan Z in there 😀