need help to Finish my first Rig of 8 GPU titan x? (perhaps somthing is missing?)

[Flomac]

http://i.imgur.com/DXek3bS.png
http://i.imgur.com/sM6uZyO.png
http://i.imgur.com/MwZMle0.png
http://i.imgur.com/wCfxEii.png

i dont expect nothing to be honest, just learning thats all

Ok, an air duct, not an air dust...passive cards only, but you know that already

and after what °C it can hurt the performance?

That's flexible and depends on the temperature-taget you're setting. But you usually ramp up the fans and let them run at high speed, so the TT doesn't affect you.