Epson Epson - Manual (Page 171)

Processor Upgrades
The computer’s processor can be upgraded by replacing the
existing processor with a faster one. The following table lists
supported processors and voltages.
Supported processors
When you replace the processor, you need to check the settings
of a number of jumpers. See “Changing the Jumper Settings” in
Chapter 4 for a complete list.
Specifications A-9