MB lights/light strip are flashing. Not the debug lights, they are fine. I have this happening on 2 MSI boards Z270 SLI plus and Z270 PRO A.
here is someone eles with the same issue:
First I thought it could be the PSU but in this video the PSU is not a EVGA.
However, I have tried 4 different psu EVGA GQ 750. If i only plug in the CPU and Motherboard connections then it starts BUT obviously I need to connect SATA and VGA.
When the SATA is connected, the MB does not boot but instead it does this flashing.
if i boot via USB (no SATA) everything seems OK.  Note I am using the 'GQ' cables as I have heard G2,G3 cables are different and not compatible. (I have a few of the later PSUs also).  Also , The MBs start with the other PSU G3. 
So is the problem the PSU (SATA) or MB issue ??? I'm thinking SATA rail.  Hope you figured this out Thanks

Good Point Sajin, the MB did start up and and there was no disco show when i disconnected the SATA data cable.  
Also prior, the Sata data cable was getting hot when the PSU sata and data sata were connected.
But a warning out there... I did alot of testing with the other MB and 3 PSU and at one point they were cooking drives. 
So in the mean time i tried 2 other SATA power cables. i have a bunch  because of purchasing 4 of these GQs.  And BINGO it started again and again.  So looking at the PINs, i can see they are different.
You can see the top right Pin is blank which really matches G2 and G3 cables. (i do have many of these PSU)  

 
Sajin, can you confirm that GQ and other G series cables are not interchangeable?   For future readers.
 
Also, should I be worried about the VGA cables. I did a multimeter beep test and some results were different here too.
 
I bought these PSUs to run GPUs only. Hence the VGA cable concern.  Thx .....
 

thats your reply!!!!... did you see you that you sent me GQ cables that matched G1,2,3 etc with IN A GQ Package!!
This is not my issue!!!! 
You cooked 2 SSD drives because or you corporate incompetence.  
i would have accepted on the SSD lost but now  the people need to know 
WE will go #evga #evgaSucks #evga750  #evga1000  #evga650 #evga550 #evga650 #evgaDoestnrepectU
#EVGASUSK
...dont worrie...this is going on more forms. 4
 
You had you chance Sajin....I'm NOT worried about the BEEP test on YOUR cables. 
Everyone who bought your crap should be too,  as I'm sure you wont cover burnt out compents
 
All good...do you repesent EVGA.... ??? 
sleep well
 
 

GordoD
did you see you that you sent me GQ cables that matched G1,2,3 etc with IN A GQ Package!!

No, as I'm not an evga employee.