80 Mhz crystal and Heat sink and fan fitted. No smoke however I forgot that by upping the crystal for the PPC you up the bus speed and it's too much for the memory. Whilst it does workish in 3.9 it's very unstable and OS4.0 doesn't work at all. Nothing ventured nothing gained. It's a good job I used the sockets. Still I'm trying the 040 at 40Mhz for a Sysspeed module for a bit. I may try altering the multipliers to at first goto x4 @266.67 Mhz at first and if i can do that try x4.5 with a 60 Mhz crystal for 270 and then with a 66.67 crystal for 300Mhz although I'm not sure if that would work. The web site that I use advised that it wouldn't but that may be because he was using a x5 multiplier.