I can confirm that you can put in more than 256GB in a Precision 7810. I replaced two 32GB DIMMs with 64GB to get a grant total of 320GB. I used SNP29GM8C/64G.
I some places saying the maximum memory in the T7810 is 2TB but most suggest it is only 256GB. I have the two processor system currently with 256GB and I want to try and buy say 4 128GB DIMMS to put in the system. Anyone done something like this and can say if it worked?
Maximum Memory in Precision T7810