Overclocking your System


The CPU and the system are clocked by a 40MHz Oscillator. This oscillator can be easily replaced with a 48MHz or 50MHz version. I know several 3/60 running fine with 50MHz oscillators, one is running 24h per day for a couple of months now. If your SIMM's are fast enough and you don't have a CG4 in your machine you can probably try even higher speeds.

I've tried a 59.9MHz and 60MHz oscillator, and the machine ran for a few minutes, but failed, when it heated up. The speedup was NOT proportional to the clock frequency; the machine was only as fast as with 50MHz. There seems to be a point, where a higher clock frequency results in a slower CPU speed (perhaps, because a second wait state has to be inserted). With a 68030, this point is between 48MHz and 50MHz. I wasn't able to try a 55MHz oscillator, because the loaned one was defective.

Hey guy's! Clean the airflow from dust and replace the old fan by a new (better) one! The machine will die horribly, if you don't take precautions against overheating!!!


The oscillator's ID is U110. In the picture below you can see U110 (the upper one) and it's environment.


The CPU-Performance grows in relation to the clock-speed and I've got a better filesystem-throughput on my SCSI-Harddisk. I think this resluts from clocking U606 at the new speed, too.


Drawing by Jerry Koniecki.

How you easily can see most of the system-clocks are generated by U110 and so replacing this one gives your system a nice speedup (and warmup).

Peter Koch