okay, so I got cloudninjas dot com to help me test this config, and apparently it works!  they were able to max out 6x64gb (384gb) for T320.   I've nudged cloudninjas to test the RAM config on other E5 2400 v1 / E5 2400 v2 series servers too (T420, R320, R420, R520) to test it out if it also works on those.   Struggled a lot as I can't find any confirmation online (did a lot of reading, a lot of deduction by checking that Supermicro X9 series supports 64gb LRDIMM) to reach this conclusion   Again, its not official solution/recommendation by Dell, I'm using this for homelab but yeah it works.
I am currently using 2 x 32GB 8Rx4 LRDIMM on my T320, I wanted to buy 8Rx4 LRDIMM 64GB instead but was advised by the vendor that it is not compatible.   Can Dell help to clarify if Poweredge T320 supports LRDIMM 64gb?   The associated part number would be HMTA8GL7AHR4A-H9. [URL]   Thanks.
PowerEdge T320 Memory Compatibility LRDIMM 64GB