User Guide
Mac Pro Troubleshooting — General Information 151
Memory Riser Card Diagnostic LEDs
Both of the memory riser cards include diagnostic LEDs for each DIMM. Each of the LEDs will
light if it detects an issue with the corresponding installed DIMM. These LEDs will also ash briey
when the computer is started up or shut down and when it goes in and out of sleep mode. This
is normal behavior.
Troubleshooting:
Shutdown and restart the computer. •
Try reseating the DIMMs. •
Check memory installation instructions for proper installation order. •
Swap aected DIMM with known good DIMM.•
Try moving DIMM to another slot (within the same bank of two) to see if the failure LED •
follows the DIMM. If so, replace DIMM with known good DIMM.
Video Card Diagnostic LEDs
The Radeon X1900 XT video card also has diagnostic LEDs. These LEDs will also ash briey when
the computer is started up or shut down and when it goes in and out of sleep mode. This is
normal behavior
T_Fault LED
Normally o, this LED lights up if the graphics chip gets too hot.
Troubleshooting:
Check that the front fan is working. •
Try re-seating the card in the PCI Slot. •
Make sure the card’s auxiliary booster power cable is connected (if there is one). •
Re-boot the computer. •
Try a dierent video card. •
Replace the video card.•
Ext_Power LED
Normally o, this LED lights up if the auxiliary power isn’t being supplied.
Troubleshooting:
Make sure the card’s auxiliary booster power cable is connected (if there is one). •
Check connections from the power supply to the logic board. •
Try a dierent auxiliary power cable. •
Try a dierent video card. •
Replace the video card.•