Sometimes, the FSB detection in OS X (especially prior to 10.4.8) could be wrong, you may need to set the correct value manually.To get the correct value, in the Terminal:
$ sysctl hw.busfrequency
this returns the bus frequency, you need to convert it to speed by:
<frequency> / 4000000
After you get the FSB value, open the file:
/Library/Preferences/SystemConfiguration/com.apple.Boot.plist
edit the [...]
