Quadro K4000 performance difference on PCIe 3.0 x1

Hi, I wonder if you can advise please...?

I'm not sure if this is a Quadro based question, or a SolidWorks based question - so I'm asking both parties for input.

I am looking to buy a Quadro K4000 for a CAD computer - specifically for running SolidWorks. The motherboard I have earmarked for using on the system has a PCIe 3.0 x16 slot available for the Quadro GPU, however, if I populate the M.2 slot, the PCIe 3.0 x16 slot drops to a PCIe 3.0 x8 speed.

The architecture of the K4000 only requires PCIe 2.0 x16, so in theory, the PCIe 3.0 x8 speed should be fine... but will the reduced connectivity have an impact on the performance?

My SolidWorks needs are mainly 3D modelling (currently 2013, but will be on 2014 / 2015 once the rig is built), and 3D rendering of the models. There may be some simulation in the future, along with some Inventor work as well.

James