Psu recommend

[wezz_playzz]

I'm getting a ryzen 5 3600x, 5700 Xt and a b450 tomahawk max what PSU recommendations do u have and reliable brands and wattage I should go for. I used a PSU calculator it suggested 80+ white is this reliable as a PSU as many people go for bronze silver gold platinum.

thank you

[MarvintheParrot]

1 minute ago, wezz_playzz said:

I'm getting a ryzen 5 3600x, 5700 Xt and a b450 tomahawk max what PSU recommendations do u have and reliable brands and wattage I should go for. I used a PSU calculator it suggested 80+ white is this reliable as a PSU as many people go for bronze silver gold platinum.

thank you

NEVER use PSU calculators. They just dont work. Instead, multiply the TDP of each power consuming part (CPU, GPU) and multiply them by 1.5, so a 95W CPU would add up to ~150W. A 5700xt would be ~350W. I would recommend a 650W PSU for that specific build. And gold or above is the target for all PSU. 

 

https://www.amazon.com/Seasonic-SSR-650FX-Modular-Warranty-Compact/dp/B077J9QTDR?th=1

 

I have used this one before, its great and has a 10 year warranty. Its a little pricey, but that's what you pay for a safe PSU, high rated PSU, good wattage PSU, and a 10 year warranty.

[bellabichon]

1 minute ago, MarvintheParrot said:

NEVER use PSU calculators. They just dont work. Instead, multiply the TDP of each power consuming part (CPU, GPU) and multiply them by 1.5, so a 95W CPU would add up to ~150W. A 5700xt would be ~350W. I would recommend a 650W PSU for that specific build. And gold or above is the target for all PSU. 

 

https://www.amazon.com/Seasonic-SSR-650FX-Modular-Warranty-Compact/dp/B077J9QTDR?th=1

 

I have used this one before, its great and has a 10 year warranty. Its a little pricey, but that's what you pay for a safe PSU, high rated PSU, good wattage PSU, and a 10 year warranty.

I'm a little bit curious about your math here. Why multiply the wattages by 1.5? Also, the 3600x is an 80W chip, not 95W.

[MarvintheParrot]

6 minutes ago, bellabichon said:

I'm a little bit curious about your math here. Why multiply the wattages by 1.5? Also, the 3600x is an 80W chip, not 95W.

really? On the AMD website, it says 95W for the 3600x. 1.5 is just a safety factor. it accounts for the occasional power spike.

[seban]

3 minutes ago, MarvintheParrot said:

really? On the AMD website, it says 95W for the 3600x. 1.5 is just a safety factor. it accounts for the occasional power spike.

Damn thats very informative for me. Thank you, i'll use that in the future.

[bellabichon]

6 minutes ago, MarvintheParrot said:

really? On the AMD website, it says 95W for the 3600x. 1.5 is just a safety factor. it accounts for the occasional power spike.

I don't listen to manufacturer TDP. They have lawyers to deal with. Tom's and TR both say 80ish. As for the 1.5 thing, still seems a bit excessive to me. Your average CPU or GPU isn't going to see a random spike of half of its peak power consumption. 

[MarvintheParrot]

15 minutes ago, bellabichon said:

I don't listen to manufacturer TDP. They have lawyers to deal with. Tom's and TR both say 80ish. As for the 1.5 thing, still seems a bit excessive to me. Your average CPU or GPU isn't going to see a random spike of half of its peak power consumption. 

Its just to be safe, but you can really do whatever you want. It also compensates for upgrades down the line such as a new GPU or CPU.

[camieabz]

(Long post - TLDR below)

 

Three reasons really. It allows for surges and spikes, but also for future small additions, such as extra storage or more RAM. Lastly, it creates the potential for the PSU to operate at it's best efficiency. Imagine a system that TDP calcs at 465w. So you get a 500w PSU, and it runs at 93% load when the system is running to the max. PSUs tend to be most efficient at 50% to 65%, so if you multiply 465 x 1.5 = 698, so a 700w supply runs at 67%, and is still not perfect, but it's far better. A 750w supply would be 62%, an 850w would be 55% and so on.

 

The more load, the hotter it gets and the less efficient it gets, and the efficiency of the PSU degrades over time (ten year warranty?). Best to keep it from getting too hot. A system running at 80-100% load all the time will put out a lot of heat. The efficiencies at 115v tend to worse than 230v as well, so there's that to consider too.

 

What is efficiency? if a PSU is rated to run at 80% efficiency, for the demand of 465w, it will drain 582w from the wall (think electricity bills and if so inclined, green energy). That's 117w wasted to heat and noise. See the 80+ cert requirements:

 

https://en.wikipedia.org/wiki/80_Plus#Efficiency_level_certifications

 

So to be 80+ certified a PSU should be 80% efficient at 20%, 50% and 100% load, which sounds good, but it's the bottom tier of cert levels. I would always recommend an absolute minimum of bronze, and for most enthusiasts, a minimum of gold. So gold would get 90% efficiency at 50% load, or 517w real draw for your 465w TDP estimate.

 

Now for the reality. You're not going to be running the system at 100% all the time (or even ever). In a perfect world, you would build the system, measure the load at idle and max load, and then go buy the ideal PSU, but you can't. So you try to get a PSU that's efficient at low, medium and high loads (i.e. gold, platinum, titanium rated PSUs).

 

If you can, try to get an estimate for all the kit TDP (e.g. 465w), and an estimate for the CPU and GPU wattage at idle. Some reviews will show idle power draw. My gaming system's 2700x hovers around 15w idle with a TDP of 105w, so take 90w off the system there. The GPU tends to idle at 5% of it's 235w TDP, which is 12w, so there's 223w saved there too. My PC's spec was 464w TDP estimate, but take off the 90w and the 223w, and that gives us an idle of around 150w (20% of a 750w PSU). So the system will operate somewhere between 150w and 465w.

 

50% load on the PSU demands 300w at idle to 930w at 100% system load. Again the reality is that 100% system load is unlikely, so let's make it 75%. That would be 349w, and at 50% PSU load, that would require a 698w (700w) PSU. I got a 750 Gold PSU for this system, and I'd say it's probably a little overkill, but not really. Those surges and spikes, and any future upgrades are covered. The power draw from 150w to 465w uses 20% to 62% of the PSU. One other bonus is that the fan isn't going nuts all the time, and cuts out on low loads, which extends the life of the PSU fan.

 

TLDR

The 1.5x rule basically builds in some overhead for the future, and takes the edge of excess heat, and makes more of the potential efficiency. All PSUs lose electricity to heat, but a higher rated PSU from a reliable vendor will minimise this issue.