So GPU-Z will show individual power draws for 8-pin#1, #2, and #3. I'll take a wild guess and say #2 is the middle one. But I don't know which is #1 and which is #3. I've searched on Google, but can't find a schematic to show this.
 
So why do I care, and does it really matter? Probably not...but I have a somewhat unusual setup. I've got a 12VHPWR connector coming from my power supply, and then a rather odd Comeap adapter that converts 12VHPWR to two PCIE 8pin (the opposite direction of what you usually see). Then I have another separate PCIE 8 pin cable direct from the power supply that provides the 3rd 8pin.

GPUZ generally shows a balanced power draw between 8pin #1 and #2, then #3 is often less. Ideally I'd like to run the separate 8pin cable to #3. I just don't know which connector on the gpu is #3.

If anyone knows for certain, please let me know. Thanks.