stuck in this forum still, so please bear with me. I want to jump into mining, and I am trying to spec out a rig for myself. I would like to run 3 GPUs per box, but it is difficult to find motherboards that have 3 PCI-e slots that can run at 16x. If I run them at 8x or even 4x, will I take a substantial hit in Mh/s?
Yep, you can run GPU's for mining at x1. Grab a few PCI-E x1 extenders, cut the side off (OF THE EXTENDER, DONT CUT YOUR MOTHERBOARD!) so the GPU will fit in, stick a wire in it like so
and then put the extender in, and plug the GPU into that, should work like a charm then