[linux-audio-user] CPU clock - beware

This might not be an appropriate place to ask this question, but I've gotten help here before on a number of things... So I have an Athlon XP 2500+ and a DFI motherboard with the nvidia nforce2 chipset. I have run it for almost a year, and it has been rock solid under linux (not as much under Windows), red hat 9 and planet ccrma kernel/drivers/software -- 2.4.26-1.ll.rh90.ccrma. RME hdsp multiface, and um... 2x512MB Crucial unbuffered DDR400. Great, except - I have never been able to set the appropriate bus clock in the BIOS without linux becoming COMPLETELY unstable. If I set it to the published specs (166Mhz bus, x11 multiplier == 1.83Ghz), I usually can't even get through the linux boot process; if it makes it through the boot process, it will usually hang at the NVIDIA screen, or at the signin... if it makes it past that, I can sign in, do a few things in a shell, but then after about 2 minutes at most, the system freezes. And we're talking about a hard freeze - no ctl-alt-del, no ctl-alt-backspace, no response at all. Windows runs as fine as it ever has. The only way I can get linux to run stably is to underclock the system at 100Mhz, which puts my CPU clock at a wimpy 1.1Ghz. Setting the multiplier higher than 11 but maintaining the 100Mhz bus clock results in the same problem. I thought for a moment that the memory clock and the bus clock weren't syncing, so I set them in 1:1 ratio - linux still hates it at any frequency. You can lock AGP at 66Mhz, still nothing doing. This is a board and proc combo that has been renowned for mega overclocking - I shouldn't have to underclock it to have things run right. Windows runs fine so I'm wondering if it's not a problem in my kernel or distro rather than the bios or hardware. I have not as yet tried to boot another kernel, but I will tomorrow when my mind is clear (I just started trying to fix it today, and I'm weary). Any ideas about it, or about where I could read to fix it? Thanks, Matt