NEC POWERMATE P2166 Manual page 162

Move the jumper to the number of PCI slots you want
4.
enabled.
NOTE
In minitower configurations, when the jumper
is set for Two PCI Slots, the shared PCI/ISA slot
functions only as an ISA slot.
!
Do not change the jumper from Two PCI Slots
(Default) to Three PCI Slots in minitower network
configurations. Changing the jumper affects network
functionality.
PCI Slots J4G1
Two PCI Slots
Jumper 4-5, 1-2
Three PCI Slots
Jumper 5-6, 2-3
If you removed any expansion boards, replace them (see
5.
"Replacing Expansion Boards" in Chapter 3).
CAUTION
4 6
1 3
4 6
1 3
Change PCI slot setting
Setting System Board Jumpers 5-13