Epson EL 486UC - Manual (Page 54)

Before you install SIMMs, check the following guidelines to
ensure that they will work properly:
Use only tin-plated, 36-bit, 72-pin, fast-page mode SIMMs
that operate at an access speed of 70ns (nanoseconds) or
faster. Be sure all the SIMMs operate at the same speed.
Use the correct SIMM configuration to add the amount of
memory you want. See the table above.
Inserting SlMMs
Follow these steps to install SIMMs:
1. Refer to the illustration on page 3-5 to locate the SIMM
sockets near the front of the system board.
2. Remove any option cards that may be blocking your access
to the SIMM sockets. (See page 3-17 for instructions.)
Installing and Removing Options 3-11