Some BIOS include this option:
Write Data Early: Enable/[Disable]
For example, in the Supermicro BIOS' it's under Advanced/Chipset/Northbridge, where it's disabled, by default. (Unfortunately, the Supermicro manual doesn't explain this option.)
What does 'write data early' mean is this context?
What are the advantages of enabling/disabling it?
It should be a timing optimization for buffered and/or fully buffered DIMM. It basically allow to lower the latency by some cycles. I can't find anything Intel specific, but you can give a look at this Google patent