It's hard to say since you know that overclocking is never guaranteed. However, you can try a few things to determine if your overclock is really being hindered by the processor instead of some other component. Some motherboards don't really like FSBs higher than what they're spec'ed to run at. Although 146MHz isn't really that much higher than the spec for that mobo (133MHz), it could be a possible suspect. Also, what kind of RAM are you using? If it's PC2100, then it is possible that the RAM just doesn't want to go much higher than 133MHz DDR. If you really want to find the limit of your processor then I suggest you unlock it and keep the FSB at 133MHz and just raise the multiplier in small increments. That way you'll be isolating the problem to only the processor since everything else will be running in spec. Of course if it still won't go any higher than 1.6GHz then you'll just have to live with it.