Well just bit the bullet and loaded up the new 0602
BIOS and after having the same memory problems that seem to be plagueing loads of other people I have immediately been able to boot with an 8x multiplier and a 450MHz
FSB (on Q6600 G0 processor). I had been able to use these settings for about a week before things started to go wrong, then couldn't get system to boot with anything above 400Mhz
FSB.
Next I need to try putting back in my other 2x 1GB modules (total of 4x 1GB).
Might wait a while before doing this as not wonderfully confident on this one and don't want a repeat of last few days issues.