This is some really strange behaviour. Installed a second GPU GTX1050 in PCIe 3 slot, left existing graphics card in PCIe1 slot but disabled with the onboard jumpers. PC has been running since yesterday without any crashes or issues. Then decided to disable PCIe3 via the jumpers and re-enable PCIe1 and everything is still running without issues ~ 5 hours so far. I am really at a loss as to why everything would work with 2 GPU cards in the MB with one of them disabled. Something else which is strange is that the fans on the GTX1050 run at 100% even though the PCIe slot is disabled.