In order to save money, I have decided to buy an old used workstation pc with a 3rd gen or 4th gen i5-i7 CPU and 8-16 GB ram. I plan to take the motherboard out, put it in a nice case, add a new power supply, and install a GPU. There is one thing I am not sure about. If I install a modern graphics card in one of these old workstation motherboards, will it be fine or will the motherboard not support it? For example, I buy an old Lenovo desktop and install a GTX 970, will it work? (PCI power connectors are not my concern.)