I have been reading a lot of things in the internet today about power supplies and I still cannot come to a conclusion on what exact PSU should I buy. The image below shows what I think is my power needs.

[![enter image description here][1]][1]


1.) There are several power supplies that have, for instance, 500w, but the price range varies hugely where there are more expensive power supplies with lower wattage than the cheaper ones. Isn't the wattage the main thing that most people refer to when buying a PSU for their PC needs? Why do I need to consider 80 bronze vs 80 gold? Full modular vs not? 

**[80 Bronze]**

Seasonic ECO PLUS 500, 500 watts - $43.78

Seasonic ECO PLUS 600, 600 watts - $51.27

Seasonic S12II, 520 watts - $58.95

Seasonic S12II, 620 watts - $68.94

Seasonic M12II, 520 watts, Full modular - $68.94

Seasonic M12II Evo, 620 watts, Full modular - $77.19 


**[80 Gold]**

Seasonic S12G, 550 watts - $77.19

2.) What is the cheapest possible PSU I can get without the risk of destroying my RX 570 GPU or any other components in my computer? I do not want any super high quality power supply that is expensive or anything that will end up destroying my components. Can I use an old (10 years old), generic, working PSU (my current one) that is like $10-$15 cheap that has 600w, but combine it with a surge protector and not risk my components from being fried? I only had a built in GPU in my motherboard until now where I plan to buy the RX 570. So I never had large power needs.

3.) What is an affordable and/or best way to make my computer's components robust from being destroyed? Such as a power surge and etc.


  [1]: https://i.sstatic.net/2JUYY.png