XPS 8500, possible to put a modern PSU?

I am wanting to replace the terrible 1GB Radeon HD 7570 in this with a GTX 1080, but the PSU is only 460W and I don't really trust that it will support the GTX 1080. Could I put a MSI MAG A550BN in or should I just undervolt the GTX 1080? If no because of proprietary , could I fix that? I don't have much money so I would prefer not to replace the entire PC. The GTX 1080 and the PSU I listed are in a budget PC part list I made, so I am just trying to stick to that while still having a PC. The GPU is coming in the 10th of June. I ordered it a bit ago because I didn't think of how old the PSU is. Sorry if this is a dumb question, I just really need to upgrade this thing at least a little bit.