I have Avermedia C985 capture card, I know it's so old but at least it's cheap and useful. Motherboard is B450 Tomahawk, it has 5 pci and 2 of them for GPU. When I take first one for GPU and plug capture, PCs led and fans starts but does not get BIOS screen or anything, just black screen. I switched GPUs PCI (I mean second one) then plug capture card, it worked great but my GPU performance reduced. Do you guys have solition or advice?