The motherboard has a feature that enables you to locate a faulty DIMM, even when power has been removed from the system. A SuperCapacitor provides sufficient current to keep the faulty DIMM locating circuit active for several minutes after the power cords have been disconnected. If you see the DIMM Fault Remind Power LED illuminated, the feature is still available. By pressing the Remind button adjacent to the lit LED, any faulty DIMMs are identified by their respective LEDs lighting.
The Remind button is located on the motherboard, just under the PCI mezzanine board, against the left wall of the chassis. The Faulty DIMM LEDs are located to the rear of each DIMM slot. See Motherboard, DIMMs, and PCI Board Locations.