which usb ports do you have the big fans connected to?
as i can see from your pictures, they are not connected to the gekko usb hub
and unfortunately i do not own an usb meter and therefore cannot measure the voltage

I don't get any power for my fans from the Gekko hub. I use my PSU's 4pin plugs and power all of them off of those.
And as posted above, if you are not going to buy a USB meter I wouldn't suggest pushing it to those speeds. You can get them on Amazon for less than $20 and they are Amazon prime. I got mine the following morning.
this is a very good idea.
could i also connect the fans to my breakout using a 4 pin - 6 pci-e adapter (if there is one)?