IBM x3250 - System M3 - 4251

System-board external connectors
The following illustration shows the external input/output connectors on the system
board.
Serial (com1)
Video
Ethernet connector 1
USB connectors 1 & 2
Ethernet connector 2
USB connectors 3 & 4
SW1 (NMI button)
Microprocessor
Heatsink
Orientation
DIMMs DIMMs
22 IBM System x3250 M3 Types 4251, 4252, and 4261: Installation and User’s Guide