Co-author of BufferMod's modified PremaMod BIOS here.
BufferMod gave two goals to me:
1. Unlock (or fix compatibility in other words) 16GB memory sticks, therefore the total supported system memory is raised to 4x16=64GB.
2. Unlock/fix PCIe 3.0 link speed support, raise it from 1.0/2.0 to 3.0.
I do not own a P570WM(3) myself. BufferMod and several other friends of him provided help to test the modified BIOS out.
Very sadly, several P570WM motherboards were damaged because of residue electric charge in the capacitors, and, something especially worthes noting: there are SO-RDIMM sticks, which are not compatible with normal SO-DIMM slots. After installing such SO-RDIMM sticks to P570WM's SO-DIMM slot, the motherboard bricked when powered on.
Let's come back to the topic of supporting normal 16GB sticks. There's a module named "IvtQpiandMrcInit" in the BIOS which, just as its name suggests, is in charge of memory initialisation. There's an internal "supported SPD" table in that module, possibly is the thing that Intel calls "plan-of-record" ("POR") internally. And then there is a function in charge of checking the SPD data against that supported list. I patched the machine code to skip such checking, so that 16GB normal SO-DIMM turned out to work fine with modified BIOS on P570WM(3).
As for PCIe 3.0 support, if I recalled correctly two modules of the BIOS needs to be modified. One was replaced entirely, and the other was patched. (At this time of posting I cannot remember the exact details sorry)