120MHz 604e Card Info

These cards have a 40MHz oscillator that gives a 120MHz machine through a 3x multiplier, so the bus is running at 40MHz, and that leaves a fairly large area to work with since bus maxes are around 55-60MHz these days. Most cards will make it to around 165MHz if you have a fast L2 cache (10ns), or remove the cache, or about 156MHz if you have a slow L2 cache and want to keep it. So replacing the 40MHz oscillator with a 55MHz oscillator gives you a 165MHz card. Mod 1 and Mod 2 are the best ways to clock chip these machines since the initial oscillators are the metal can type.