Sorry, mlaine, I didn't mean for you to disregard your second ram stick for good. I was only trying to help you figure out the hidden potential of your system in terms of RAM/board/CPU oc'ability above fsb=160 so you can zero in on the culprit. And to an extent you have as now you know that your 2.26 CPU might be restricting you from going above FSB=160 and your plan to pursue a higher ratio is the right one since you'd be able to oc RAM higher while keeping your CPU happy underneath your 160 FSB threshold.
It looks like your RAM is truly capable of DDR400 as that -50 suggests 1000/5*2=400 (*2 for DDR). Check this
link and see if you can decode the rest of your part numbers on the
Kingmax web site to determine the exact CAS settings that will work at or near DDR400.
In terms of dipswitch settings have you tried the following conbinations
DS1,DS2,DS2,DS3,DS4,DS5,DS6
OFF, OFF, OFF, OFF, ON, OFF or
ON, OFF, ON, OFF, ON, OFF
and see if they work in jumper free mode. Start by relaxing your CAS settings to their slowest settings possible and FSB 133 in the CMOS with these and see if you're able to achieve that 3:4 ratio. Also set your AGP/PCI to auto if possible instead of locking them.
Good luck!
Peace