Hi Dschijn,
>I have actually found a post with the same graphics card that functioned, so its should not be a problem of the card normally, and y have tested the graphics card in a pc successfully.
>I use the dell da-2 power plug according to the guide on this forum, and a power supply pc brand new 750w advance purchase yesterday, i use the 2+6 pin for power the only 8 pin port of my graphics card, i have tested the three yellow cable + 12v with a multimeter which announced 12.32v.
(There are the same problems with the two PSU)
>The barrel plug is connected with the yellow cable to the middle, and black for the end of the barrel.
>And if I run the script under OS X after the second step, I have the error "Thunderbolt device is connected, but no external GPUs detected.".
So I do not see or can come my error, I will test with the graphics card of a friend this afternoon, this may be the case that has problems, yet it reacts well when I plug and unplugged the thunderbolt.