Our Spanish friends from
Entremaqueros have published an article describing the complete mod of a Powermac G4 Quicksilver. They modified everything, from the CPU overclocking thanks to "dip Switch" to the exchange of the cooling system. In
July 2001 (only in French, as hardmac did not exist yet), we published an article explaining how to overclock this model, but
Entremaqueros brought it to a the end.
Such hacking will not be possible on MacIntel, Intel has locked the multiplication factor of its CPU, and nobody has found a way to increase the frequency of the FSB on our MacIntel motherboards. If you want to dig into, we can tell you that the bus frequency information is hidden in the SMC.