What’s the Most Reliable PSU Calculator for Upgrading My GPU?

I’d suggest going for a quality 850W PSU. You can check out SPL's PSU Tier List to help you pick the right one. It’s worth investing a little more upfront to avoid issues down the road.

I have a similar setup as yours and upgraded my PSU from 650W to 850W when I switched to a 5070Ti just to be safe. It’s a good idea to future-proof your build, especially with a PSU upgrade. Better to have some headroom than to be cutting it close.

A good approach is to take the maximum power draw of your GPU and add the PPT rating of your CPU, which I think is around 142W for yours. Then, add another 100W for the rest of the components unless you have something not typical. For a 5070, I’d lean towards 750W, but since A-tier 850W models have been around $80 lately, it’s not a big jump in price.

There isn't a truly accurate PSU calculator out there because power demands from parts vary. Most calculators use TDP which isn't always reflective of actual power draw. For your case, the RM650 should be sufficient for a 5070Ti since it generally has a sustained draw of around 300W, peaking at 350W. That said, you'll be fine unless your build runs unusually high on power.

It’s true that PSUs are often the longest-lasting component in a build. In my experience, the only time I’ve had to buy a new one was when I went cheap at first and ended up needing an upgrade later. I really recommend spending a little extra and getting something more robust than you think you need; PSUs are relatively cheap for the reliability they provide.