Check this out from <A HREF="http://www.asusboards.com/forums/showthread.php?s=&threadid=42761&perpage=15&pagenumber=5" target="_new">Prometheus at Asusboards</A>:
Prometheus
Section Moderator
MORE Memory Ratios (post #72)
MORE Memory Ratios
There are quite a few memory ratios available on the Abit that are not revealed until you adjust the N/B Strap. The N/B Strap is a setting in SoftMenu that allows you to alter the options available for memoy ratio AND memory timings.
Available settings at each N/B Strap Setting:
400 - 3:4, SPD
533 - 1:1, 4:5, SPD
667 - 5:4, 1:1, SPD
800 - 3:2, 5:4, 1:1, SPD
In practical terms this means the following memory ratios are available at ANY FSB, depending on the N/B strap setting: 3:4, 4:5, 1:1, 5:4, 3:2, SPD This means at 180FSB with a good 2.4 - 3.24GHz - you could choose the foolowing Memory speeds by varying the N/B Strap: DDR480, 450, 360, 288, 240, SPD(rated memory speed).
In addition I have found that the N/B strap chosen also alters the point at which the board overides memory settings and the overide used. The net result is MUCH better than first supposed when the timing override issue was first mentioned last evening.