It seems to me that 1.60 is more unstable. The FSB jumps back and forth within a 1Mhz range (like 266.33, 266.58, 267.2, etc) even with SpeedStep disabled.
The increased memory bandwidth surely helps the CPU. It seems that the Quads are starving for bandwidth. With 3:2 the max I got was 3.27 in Cinebench @ 3.26Ghz, now the max is 3.61 at the same speed although it isn't very stable. I'm letting it at 3.24Ghz for the time being (270x12).
CRUNCHERS - 1090t - 2x1055t - X4 620
OCTANUX - Conroe865PE - QX6800 - 4GB DDR-400 - HD4670 AGP - Audigy 2 ZS - Physx PPU
phenomenal - AM2NF3-VSTA - 965BE - 8GB DDR2-1066 - HD3850 AGP - X-Fi - Physx PPU *WIP*
Green Tea - 939A8X-M - FX60 - 4GB DDR-500 - 7950GT AGP
Re-build - CT-6VTA2 - PIII 600E - 384MB PC133 - Voodoo 5500 AGP - SB16 ISA
RB scraps - IC7-G - P4 3.4E - 4GB DDR500 - HD2600XT AGP - X-Fi - iRAM *WIP*