Note: Sun does not officially support using Ultrasparc-II CPU modules faster than 300 Mhz in Ultra-30 systems. All responsibility for damage to filesystems and data rests solely with you!
According to Sun's official engineering notes on the Ultra-30 system, the only CPU modules which are supported are the 250 Mhz (aka x1190a and x2230a) and the 300 MHz (aka x1191a and x2240a) Ultrasparc-II CPU modules.
The Ultra-30 motherboards have a jumper (J3001) which is used to select the clock divisor so as to allow older 167 Mhz (aka x1187a and 200 Mhz (aka x1188a) Ultrasparc-I CPU modules to also be used, although the actual hardware specifications of the machine do not make any mention of this. The jumper should always be left in the 1-2 position unless you want to use an Ultrasparc-I CPU module.
What is also not mentioned in the documentation is that it's possible to use higher-speed Ultrasparc-II CPU modules in Ultra-30 systems. Fredrik Lundholm worked on the problem and figured out how to get 360+ MHz Ultrasparc-II CPU modules to work properly...
The way to do it modify the OpenBoot PROM configuration so the OpenBoot firmware will correctly recognise the type of CPU module fitted and behave accordingly.
Personal note: It is highly recommended that you make sure your Ultra-30 system has the very latest OpenBoot PROM firmware version installed into the flash PROM on the motherboard. You can get this patch from my Sun BootROM image and OBP firmware patches page.
Is anyone able to confirm these increment settings? I know the setting for 360 MHz CPU's works since I've set up an Ultra 30 that way (with jumper J3001 set to divide by 3 mode). I'm sure there is a logical process to calculate the increment setting - does anyone know what it is?
The process of modifiying the OpenBoot PROM configuration is detailed below (written by Fredrik, not me):
At the 'ok' prompt, type 'also hidden' followed by '+cpu-speed' repeatedly until the desired frequency is reached (check with the '.speed' command) To make this speedup permanent and non-intrusive, enable nvramrc and put (from memory in Fred's Ultra-30 running at 400 MHz with a 450 Mhz CPU module): also hidden 180 at-speed in there. To enable nvramrc, enter: setenv use-nvramrc? true at the 'ok' prompt, and then use 'nvedit' to place commands into the nvramrc storage area. That should make the machine automatically come up in the right mode at power-on.
Ultra-30 OpenBoot PROM Config Changes for 360+ MHz Ultrasparc-II CPU's
If you have any further information about this process, perhaps to correct the method, or suggest a better way to do it, please let me and/or Fredrik Lundholm know.
Sun Shack data archive