I converted an older computer to a mining rig recently - i7-4770k on a Gigabyte Z87X-UD3H mobo with HiveOS running on it. I had a evga RTX 2060 KO on it initially, and would get about 32 MH/s with oc. More recently, I got hold of a 1080FE, and when I plug both the 1080FE and 2060 on to the mobo (2 PCIe x16 size slots), I get hash rates of ~30.7 MH/s on the 1080, and hash rate on the 2060 drops to ~28 MH/s with the same oc and stubbornly refuses to go higher.
Any idea what might be causing this drop in hash rate on the 2060?
The mobo manual states that when both PCIe x16 ports are populated, they operate at x8 which should be sufficient for both gpus to operate normally. What am I missing here?