And if you put 2 gpu on the same cable, if you disconnect one of the card, it start right ? only 2 gpu on the same cable make one not starting, also in the power supply "chain" is the GPU not starting the one at the end of the chain ?
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fi.imgur.com%2FfuBCtoo.png&t=663&c=6qD1ab1tSVBBBw)
In this little schematic, following scenario
All connected - which one of the gpu doesn't start ?
6+2 pin 01 or 02 disconnected, does the GPU start ?
Swaping 6+2 pin 01 or 02 between gpu 01 or 02, does the GPU start when only one connected ?
As stated before do you use the same power cable and power output of the PSU ? did you tried swaping them ?
Also have you tried to use a molex to 6pin adapter to see if that 6th GPU would start ?
Also have you put the PSU in multi-rail mode ?