Typical Intel offering is 1.5-2TB per socket. Socket scales up to 8 (though the price increase 2->4 is very steep). Memory itself is registered ECC DIMMs (which is even lower cost than consumer DIMMs/unbuffered ECCs), but to get to 1.5TB density you need low-rank (LRDIMM) modules, which gives x2 capacity but at a higher price.