i have only problems with 4:5 divider (wont boot over 480Mhz ram!), but 2:3 & 3:5
work without problems (boot with 615Mhz ram!).

Processor: E6300
Bios Revision: 0507
Memory: G.Skill 6400HZ
Configured Voltages: 1.45v vCore, 1.40v vFSB, 1.25v vNB, 1.70v vSB
Configured FSB:486
Configured Ratio: 1:1
Configured Memory Timings: 4-4-4-8