EVGA P55 FTW - Manual (Page 25)

The PCIe disable jumpers are located right beside the 24pin ATX
Connector. In default shipping configurations, all slots are enabled with the
jumpers in the left position. From top to bottom, PCIE slots 1,2,3
respectively. To disable a PCIE Slot, move the jumper over to the right
position.
Example: Remove the Jumper cap of JPE2, PCIE Slot 2 is disabled while
the rest are enabled. The PCIE Disable Function can also be extended onto
the ECP discussed later on.
Do this when the PC is turned off, NOT when it is running!
Voltage Measure Point
The motherboard is equipped with eight voltage measure point pad. You
can use a voltmeter to measure the voltage you want to know.