[SOLVED] 550W PSU good enough for GTX 1070 ti 8GB?

Solution
A decent 550W unit should have no problem with that system.
https://pcpartpicker.com/products/compare/9q4NnQ,sMM323,JfBrxr,KmgzK8/

Notice, some of the units are actually available in 650-750W variants for less than the 550W units.
All quality units. Of the ~$60 units, I'd be most inclined to pick up the 650W EVGA G2.

As an aside, the Dark Rock slim probably isn't a huge step up from the stock cooler - I'd consider running the stock cooler initially, and upgrading if you feel necessary.
A decent 550W unit should have no problem with that system.
https://pcpartpicker.com/products/compare/9q4NnQ,sMM323,JfBrxr,KmgzK8/

Notice, some of the units are actually available in 650-750W variants for less than the 550W units.
All quality units. Of the ~$60 units, I'd be most inclined to pick up the 650W EVGA G2.

As an aside, the Dark Rock slim probably isn't a huge step up from the stock cooler - I'd consider running the stock cooler initially, and upgrading if you feel necessary.
 
Solution
I agree with Barty.

If you are running stock or little oc. Ryzen cooler do a decent job. I had a 2600 for 2 weeks, my gaming temps were in the mid 50 to low 60s.

As for psu. A 550w 80+ gold rated branded like from Corsair / EVGA / seasonic/ fsp would do fine. They usually carry a 5 plus year warranty so the typically last for 2 build cycles.