Overclocking the FSB can make your system unstable. Does it run normally at default speeds? Also different versions of the bios may be more stable than others. A good thing to do after updating to a different bios version is to clear cmos and load setup defaults. Tommy ISA mod = an ISA module last worked on by Tommy that is added to the bios. It has code that updates the acpi and adds the slic in memory. It is generally safe to try and is easy to make because it doesn't require changing any existing bios modules. It is just added at the end. OEM/SSV1 = SLIC is added as a separate OEM module or nocompress module SSV3= SLIC is added in system module SSV2= For AMI only. SLIC is written over FF bytes in bios image, not in any module. If your system is unstable at normal speed with the ISA mod then you might need a different kind of mod. (You can compare to unmodded SZ17.) If it is only unstable when overclocking I think it is more likely to do with the a difference between this bios version and the version you were using previously.
Not overclocking any settings at all. The stock speeds on ram and for the processor multiplier and fsb are being used. Ex. My memory runs stock at 1066 perfectly on the unmodded bios. with the modded bios the system will restart randomly and set the speed to 800. If you get a chance do you think the OEM/SSV1 method would work?
OK it sounds like the ISA is doing something funny then. While there's no way to say for sure if an oem mod will work, I think it's worth a try. Stay posted for new mod soon!