I am currently running two EVGA GTX 780 Ti Classifieds (1- Classified and 1- Classified Kingpin) in SLI in my Coolermaster Haf X case. I was installing some new case fans yesterday when I noticed one of the LED's of the Kingpin was not illuminated. I purchased the Kingpin new from Amazon back in January of 2015. I did a search and came up with the following concerning the leds: " 
"These 5 LEDs are voltage indicator lights that can help you diagnose voltage problems with your video card. With the fan facing towards you and the power connectors facing up, the LEDs are, from left to right:
GPU - This indicates if voltage to the video card's GPU is good
MEM - This indicates if voltage to the video card's memory is good
PLL - This indicates if the voltage for auxillary components such as fans, LEDs, etc. is good
3.3V - This indicates if the voltage supplied from the motherboard via PCIe slot is good
12V - This indicates if the voltage from the 12v input from the power supply is good
If any of these LEDs are not lighting up, it indicates a voltage issue with that component or source. Checking your power supply, motherboard, or increasing voltage to the video card may help with any of these problems". 
 
The second LED from the left (MEM) is not illuminated on the Kingpin. I am running a MSI Z97 MPower Max AC motherboard (MB) with a I7 4790k CPU. The power supply is a Corsair AX1200. I have switched the two 780's to different MB slots and the problem remains with the Kingpin. Changed the power wires from the PSU and the problem remains. I did use the EVGA OC Scanner X program and ran the Fury E benchmark program with no issues. Both cards are stock and are not overclocked. There are no secondary issues while using the cards while gaming. I am using a Dell U3415w monitor. I am thinking maybe the LED is no longer working however my other 780 TI Classified is over  a year old and all the LED's work. Is there something else I should check. I will call EVGA tomorrow since their office was closed today due to the holiday. Thanks in advance.
 
 
 
It is difficult to see in the above photo, the Kingpin is the lower card and the second LED from the left is not illuminated. 

I installed the Kingpin by itself and the same issue remained. I left the case side cover off so I could see if anything changed and the LED illuminated. The LED is illuminated right now as I type this but it is not very bright. The problem is now intermittent (Stays illuminated for several hours and then while I am on the web it will go dark on me). I purchased a new PSU (Corsair AX1200I) thinking it may be a PSU issue and the problem remains.

Sajin
Since the card works fine inside benchmarks/games I would just forget about it. It's just a bad LED.

That is the direction I am leaning. There are no secondary issues with the card and everything is working as advertised.