Try 1:1 which would put your memory at 180 fsb. If it won't post, you can try a higher cpu/mem ratio, such as 4:3. I don't know what options your mobo has at 180 fsb, but if it doesn't post, just enable your cmos jumper for a few seconds with the power supply unplugged, and try a different setting. What matters most is how stable your board and memory is with higher voltage settings, and your cooling. I recently used heatsinks on the memory for the first time. Fry's had them for only $5.95. I would limit your memory voltage increase to +.2, even with heatsinks. On my P4 1.6a, I can run the cpu vcore at +.075-+.175 and the memory at +.1- +.2 without any temperature problems.