Back ● CASES O11D MINI ● What is the PCIE slot thumbscrew size? ● I want to mount my rear 120mm fan on vertical GPU kit, what is the maximum height clearence for the GPU? Didn't find your solution? Contact Tech Support Team. What is the PCIE slot thumbscrew size? Screw size is 6#32 I want to mount my rear 120mm fan on vertical GPU kit, what is the maximum height clearence for the GPU? 130mm, not limited without 120mm rear fan