The IIe needs a Revision B Motherboard or an Enhanced IIe Logic Board in order
to support double high-resolution graphics or an RGB (Red Green Blue) Color
Monitor 100. (The Revision B board differs from the Revision A board in that
the RGB signals are sent to slot 7 and the auxilliary slot.) To determine
which revision your Motherboard is, look at the back of the board behind the
I/O slots: there you'll see the Motherboard's part number. The number will be
820-0064-A or 820-0064-B; the last character tells you whether the board is
Revision A or Revision B. If the part number is 607-0187-A, it is an Enhanced
IIe and does not need upgrading.
If you have a IIe with a Revision A (820-0064-A) Motherboard and an Extended
Text card or an RGB interface card, you can have your Motherboard upgraded to
Revision B by exchanging the motherboard.