Hi Boomer 39, the quote is identical in both the manauals for the P6X58D- E and Premium it is in Section 2.4.2 in both cases on page 2.11 . The note to this item says it is important and must be followed.
You can read several posts in different forums where people are trying to use XMP 1600 where it simply won't work and causes problems. In most of the cases where there is a problem the posters in the forums have used more than 1 DIMM per channel.
Further in section 3.5 of the manuals you will see that the default setting in the AI Tweaker section of the BIOS for XMP is disabled, and the note is repeated as an advisory.
My P6X58D-E came with 6x"GB XMP 1600 DIMMS which the supplier readily changed for XMS 1300. I studied the manual very carefully so that I did not face the same problem that is obviously bugging alot of other users. In the real world the difference you experience is negligble.
The great benefit of this mobo is the 6GB SATA and the USB3 at the price you pay for this board.
Hi again, A quick cursary scan of the Gigabyte site shows that the manual does not make this point, BUT if you look at the approved memory lists very carefully they have listed whether a total of 6 DIMMs is approved or not. It needs careful study, and I have no experience of Gigabyte.
My general experience has bee that if you study the manual before you buy and only buy approved memory you do not have many problems, but this does need careful study and sales advice cannot always be relied upon.
Final thought best to buy mobo, processor and memory from the same source costs a little more but you buy a lot of insurance if you ask tt
he supplier to confirm that the chosen items are compatible.