I'm considering upgrading my computer and was curious if I would need to replace my PSU.

I found a website that will estimate need and it came out to about 560w required.

Processor: Intel i7-7700k
GPU: GTX 1080ti

Current PSU is XION brand 800w and has been in use since around 2009. I'd be spending a decent amount on the upgrade and would hate to fry everything. Would y'all recommend upgrading it while I'm at it?

I do not see why it would be a problem. I have a couple of old computer power supplies that I use as hobby supplies for +/- 12v, +5v, and +3.3v. And one to power 12V led lighting that has been left on for weeks at a time without issues.

Yes, get a new PSU. The risk of using an old PSU is that if it has a problem it can ruin the rest of your components. They don't cost that much when you consider the risk

If you're not concerned about the risk, consider that 8 years is more than you can reasonably expect to get out of a power supply. Might as well replace it now while you already have the computer apart. I checked a XION PSU and it has a 1 year warranty, not exactly inspiring when you consider that Seasonic or Corsair will offer 8-12 years typically on their efficient models. Even 5 years on a Bronze certified

Don't be cheap.

Thanks, I was leaning towards a new one. I just didn't want to waste the money if there wasn't a reason to. I've never had a PSU quit on me, so I wasn't sure.