Epson Apex 20020 - Manual (Page 120)

Inserting the Option Card
Most option cards can be placed into any of the option slots.
Some cards, however, must be installed in a specific slot. Check
the option card manual to see if your option card must go in a
specific slot. If you are installing a new video card, you may
remove the MGA card that comes installed in your computer.
The option slots are located in the back of your computer, as
shown below.
Slots 1, 5, and 6 are designed for 8-bit option cards and the
other three-slots 2 through 4—are designed for 16-bit option
cards. Option cards designed for 16-bit slots have a second
connector, as shown below.