I understand the divider part FSB:Memory but where does the Mhz strapping come into play in the BIOS?

Quote Originally Posted by Anandtech
Memory divider ratios can be configured by this function. The available memory dividers per Northbridge strap are shown in the table below.

Gigabyte GA-X48T-DQ6 Available Memory Dividers
Northbridge Strap Available Memory Dividers
200 MHz 5:3, 2:1
266 MHz 5:4, 3:2, 2:1
333 MHz 1:1, 6:5, 8:5, 2:1
400 MHz 1:1, 4:3, 5:3, 2:1
.
Leaving this function on Auto, results in the 2:1 divider being picked for overclocking by default. For manual use, we found the 333 strap 2:1 divider to be the most stable combination to use for quad-core processors. For dual-core processors, the 266 strap and 3:2 divider worked best for us.

DRAM Timing Selectable (SPD)
This is from Anandtech review of the new Gigabyte GA-X48T-DQ6

So basically it's said that for my E6750, 266 strap and 3:2 divider might work better. How so?

Note that I don't see any difference between my X38T and the new X48T in this BIOS.