Pclausen, what boards are you using for mining?
I have 2 rigs running MSI Z270-A PRO boards. These work fine with 7 GPUs (7th in the M.2 slot using an adapter)
2 rigs are running Asus PRIME Z270-A. I like these since they have 7 PCIe slots plus 2 M.2 slots, so you can run up to 9 cards. I have had good luck picking these up for under $100 used or open box.
The x4 Sea Hawk rig uses a MSI X99S GAMING 9 ACK board that I picked up used on ebay.
I have found that once you go much past 6 GPUs per rig, you start running into performance issues when using low end G3930/50 CPUs, so G4600s are better.