PCI-E 2.0 x1 Bottleneck?

[Joel]

I am interested in trying out PyFR, but I am a little confused on how much PCI-E bandwidth is required. If I am going to run, say, 3 NVIDIA consumer-grade GPUs, will running only a PCI-E 2.0 x1 link between each GPU and the motherboard cause significant slowdown of simulation run-time?

Thank you in advance,

Joel