I have been trying to overclock my system lately (I'm a real noob, though), and tonight I came across an interesting issue with my 512MB of PC2100 memory on my ABIT KG7 (AMD761-based) motherboard. My CPU is Duron 1.2GHz, but I unlocked it and I'm running at 133MHz FSB (with a 9 multiplier puts it right at 1.2GHz). I have one 256MB stick of Crucial PC2100 and one stick of PNY PC2100. I was a bit worried about overclocking the FSB at first, but I've been running at 133*9 for about a week now with no problems and hardly any temperature rise.
So tonight I decide to go into the BIOS to look at the settings again, and I notice that I've been running the memory at CLS2. I figured I'd better bump it up to 2.5, but for some reason when I ran it at CLS2.5, the system became so unstable that it crashed within seconds of loading WinXP. Apparently running my two sticks of memory -- both rated at CLS2.5 -- causes severe instability, but going to CLS2 fixes the problem. Has anyone else had this strange "issue" (I definitely am not going to call it a problem!)?