I need a budget GPU to play fornite. I'm looking for a GPU around 140$ and maybe an extra 20$ if it's really worth it. My motherboard is a Gigabyte H310M with PCIe Gen2 X2 which I don't know much about.
Your GPU slot on that H310 motherboard is Gen3 x16. From the specs page -- 1 x PCI Express x16 slot, running at x16 (The PCIEX16 slot conforms to PCI Express 3.0 standard.)