What is the most affordable PSU for my requirements?

Question

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.

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

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.

Answer 1

Sweet spot for PSU efficiency generally is operating them between 40% and 60% of their rated capability. You can look this up, see corsair for example.

The 80+ precious metal efficiency rating...

The basic 80 Plus rating means that the PSU is rated for at least 80% efficiency at 20% load, 50% load, and 100% load.

The 80 Plus Bronze rating means that the PSU is rated for at least 82% efficiency at 20% load, 85% at 50% load, and 82% at 100% load.

The 80 Plus Silver rating means that the PSU is rated for at least 85% efficiency at 20% load, 88% at 50% load, and 85% at 100% load.

The 80 Plus Gold rating meas that the PSU is rated for at least 87% efficiency at 20% load, 90% at 50% load, and 87% at 100% load.

The 80 Plus Platinum(bet you didn't know there was a Platinum) rating means that the PSU is rated for at least 90% efficiency at 20% load, 92% at 50% load, and 89% at 100% load.

the higher efficiency PSU's cost more money, the depressing feeling resulting spending the extra money on one is supposed to be offset knowing that when you leave your computer on it's wasting less power.

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 think you found it with that seasonic 500w for $43. Seasonic is good, 500w is plenty. I wouldn't hesitate to get a 400w psu to run a 120w tdp rx570 and 95w intel i5. You're not likely to find any new good name brand reliable psu's for much less than $50. A good psu that is new will cost at least $50, it's just the way it is.

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?

a surge protector that the PSU plugs into (then surge protector plugs into wall) will not prevent a PSU going bad internally and possibly breaking your computer. Your existing 10 year old 600w psu would likely be fine. you do not require a new PSU especially if it's in an existing pc and your just adding an RX570. You can buy a new psu which can go bad, don't fret it. If you're existing 600w psu has been working up till now there's no reason to think it won't continue to work. Post the make/model of your existing 600w psu.

A full modular psu is nice because you won't have a rats nest of psu cables in your tower, if you care about such a thing. It can make working inside a tower, especially a small one, much easier. More of a visual appeal thing. There is nothing more reliable about a modular cable psu vs non-modular one.

a 250w tdp RTX2080ti running farcry5 pulls around 350w on a watt meter; max power draw observed was less than 500w (~460 if I remember) running full out stress test to see what the max power draw possible was. Your 120w tdp Radeon RX570... any psu over 500w is wastefull and I would not overlook 350w or 400w psu's. But you're not likely to find them much below $50 anyway.

There's a rash of counterfeit cpu's and graphics cards having old chip's firmware rewritten to be resold as a newer model. Careful who you buy from if using amazon or ebay, which I would not. Stick with a known retailer/reseller.

Answer 2

Okay, so firstly, the difference between expensive and cheap PSU's that give out the same wattage can be a few things. There can be a difference on the 12v rail, it can be about the bronze/silver/gold/platinum rating. Basically the different ratings show different levels of reliability towards being able to constantly supply 500w for instance. I'd say there are a few PSU brands that I would stay away from, e.g Raidmax, but Superflower and Corsair are mostly good, safe choices.

Honestly, I would advise you to never cheap out on a power supply. I have seen way too many computer's die because of someone wanting to save a buck. I'd buy at least a silver rated PSU. And age also does have an effect. 10 years old? I'd stay away from that. Rather buy a 450w/550w PSU. The EVGA one in the image you supplied is perfect. If you want a cheaper option, go for the Superflower equivalent. Modularity, this is more focused on customisability. To give an example, a fully modular PSU you only have to use the cables that you need, i.e. no need for a second 6-pin cable to dangle next to the GPU.

Buying well known and trustworthy brands. Do not overclock, and if you do, have decent cooling. Heck, have decent cooling in general. As power surging go, buy a surge protector.