# Power Supply on New Computer



## imagegod (Mar 23, 2020)

I'm a newbie to upper-end tower computers...all things being equal, what are the benefits/costs of a higher-wattage power supply?

Many thanks...much appreciated!


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## colony nofi (Mar 24, 2020)

You need first and foremost to make sure that your power supply can deliver the peak amount your computer needs when everything is running.
There's folk out in this community with FAR more knowledge than me - but things to take into account :
A CPU is measured for THERMAL power when it says "135W" or whatever. The peak electrical power needs are more than this. I'm not sure what % daw builders add on top, but its significant.
GPU's take tonnes of power.
HDD's and SSDs still need to be accounted for, as do other PCIe peripherals, etc
600W+ is not unusual. 800-1000 for gaming machines often is necessary. 

There's also discussion about how efficient the powersupplies are when running close to capacity. Does their efficiency scale / do they get less efficient when running peak loads? I don't know. Its been a while since I looked into it. Power supply designs have changed a LOT since I understood them.


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## colony nofi (Mar 24, 2020)

I mean - its linus - but this is worth watching (its a corsair sponsored video)


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## d.healey (Mar 25, 2020)

Use a power supply calculator, there are several around, just Google. As far as brands go you can't do better than seasonic, but they're pricey. Next best is probably corsair, a lot of their upper end models are made by seasonic. BeQuiet are also meant to be good but I have no experience with them.

Most PSUs will have their efficiency curve shown on the product page or in the manual. Generally they run most efficient at about 40-60% load. If efficiency is important to you then get one with an 80plus rating of gold or platinum, there are also titanium rated models if you have money to burn.


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## imagegod (Mar 25, 2020)

This is all very helpful...very much appreciated. Thanks!


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## Pictus (Mar 25, 2020)

I like this calculator








Power Supply Calculator - PSU Calculator | OuterVision


Power Supply Calculator - Select computer parts and our online PSU calculator will calculate the required power supply wattage and amperage for your PC.




outervision.com





PSU review sites:
http://www.jonnyguru.com/blog/category/reviews/power-supplies/




__





Power Supplies Reviews | Tom's Hardware







www.tomshardware.com





A good benefit of higher-wattage power supply can be *silence*.
Each PSU is different, you must check a proper review to be sure!
The Corsair RMX850 (2018) up to +-*250W the fan is off* and
up to +- 600W the RPM/Noise is very low. 








Corsair RM850x V2 PSU Review: Smaller And Quieter!


Corsair upgraded its best-selling line RMx family with new models featuring smaller dimensions and quieter operation. And despite limited PCB space, performance remains similar from one generation to the next.




www.tomshardware.com








Now look at the Corsair AX1600i, up to +- 650W the FAN is OFF! 








Corsair AX1600i PSU Review


It is tough to improve something that it is already excellent, so Corsair's desire to build an even better PSU than its current flagship, the AX1500i, is noteworthy. More impressive, the AX1600i succeeds in setting new performance records.




www.tomshardware.com








For me, the Corsair RMX850 (2018) is the "sweet spot"!
Very good electronics, silent and good price.


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## d.healey (Mar 25, 2020)

If you want total silence and your peak power requirement is < 600W go for a passive fully modular PSU. Just make sure you have good case airflow.


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## RobbertZH (Mar 25, 2020)

I have a powerfull power supply for my super-quiet computer. But sometimes, when I switched it on, a main fuse in my house found the switch-on current of my computer to high and switched off (and as a result, half of my apartement did not have electricity anymore). A risk for my computer and harddisks and a pain in the ... to set all clocks in my apartement again.

After a few evenings searching the internet, I found a 230 V Einschaltz Strombegrenzer from ELV (or in English, a switch-on current limiter). 230 V as I live in the Netherlands. If you live in the USA, you need a different voltage. This solved the problem.

Reason I mention this, as the more powerfull powersupply you buy, the higher the risk that the main fuse of your home is switching off when you switch-on your computer.


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## dzilizzi (Mar 25, 2020)

Always go higher so you can upgrade. Unless your motherboard is maxed out, figure on adding RAM, more drives, maybe a PCIe card, etc.... 

One of the things I loved about using PCpartpicker.com for my build was that it calculated the power needed by what you have. I have my build out there and anytime I change something it recalculates the power so I can verify I am still okay.


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## dzilizzi (Mar 25, 2020)

RobbertZH said:


> I have a powerfull power supply for my super-quiet computer. But sometimes, when I switched it on, a main fuse in my house found the switch-on current of my computer to high and switched off (and as a result, half of my apartement did not have electricity anymore). A risk for my computer and harddisks and a pain in the ... to set all clocks in my apartement again.
> 
> After a few evenings searching the internet, I found a 230 V Einschaltz Strombegrenzer from ELV (or in English, a switch-on current limiter). 230 V as I live in the Netherlands. If you live in the USA, you need a different voltage. This solved the problem.
> 
> Reason I mention this, as the more powerfull powersupply you buy, the higher the risk that the main fuse of your home is switching off when you switch-on your computer.


You mean something like a Soft Start? I know the off-grid people recommend them for A/C units to keep from popping the system (breaker equivalent) It is probably a good idea if you don't have a good electrical system in your house or limited breakers.


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## Pictus (Mar 25, 2020)

RobbertZH said:


> I have a powerfull power supply for my super-quiet computer. But sometimes, when I switched it on, a main fuse in my house found the switch-on current of my computer to high and switched off (and as a result, half of my apartement did not have electricity anymore). A risk for my computer and harddisks and a pain in the ... to set all clocks in my apartement again.
> 
> Reason I mention this*, as the more powerfull powersupply you buy, the higher the risk that the main fuse of your home is switching off when you switch-on your computer.*



This is called *Inrush Current*, it depends on the PSU circuit design.








How We Test Power Supply Units


Our PSU reviews explore performance, noise and temperature ratings, along with the build quality of every power supply we test. Today we introduce you to our methodology, testing equipment and benchmarks.




www.tomshardware.com





Here the results of the Corsair RM850x 




Here the results of the Corsair AX1600i




Here the results of the EVGA SuperNOVA 1600 P2.
It got double the power, but +- the same Inrush Current as the Corsair RM850x


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## Nick Batzdorf (Mar 25, 2020)

I had to replace the one in my Windows machine almost exactly a year ago. You may find this thread useful:





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600W ATX power supply replacement


I need to replace what I'm pretty sure is a dead one in a PC. Recommendations? Dis-recommendations? TIA




vi-control.net





It was $75, gold, 650W.


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## Technostica (Mar 26, 2020)

The colour ratings reflect their efficiency.
I wouldn’t get something less than Gold and it’s diminishing returns after that.
Platinum is next and Titanium units are very expensive.
A more efficient design makes it easier for the unit to cool itself silently or quietly as it has less waste heat to manage.

Some units are semi passive so the fan won’t start until a certain temperature or output level is reached.
Mine is a 650w gold unit and is passive until around 250 - 300w and I’ve never heard it.
The threshold will vary a lot by model.
If using a passive or semi passive design I think it’s generally best to use a case where the psu is located at the base.
That way the heat from the other components won’t rise up towards it.

If you list the main components you intend buying you might get wattage recommendations here.
Expect a lot of variation.


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## vitocorleone123 (Mar 30, 2020)

Don't get a massive wattage PSU unless you need it - you'll be paying more for electricity. Do get Gold or Platinum rated. Do get something that's silent up until at least ~250 watts or so, which usually means a 650 - 1000 watt PSU.


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## d.healey (Mar 30, 2020)

vitocorleone123 said:


> Don't get a massive wattage PSU unless you need it - you'll be paying more for electricity.


Just for clarity. A higher wattage PSU doesn't consume more power than a lower wattage one. But if you get one that's way higher than your use it won't be working at its most efficient.

This is the efficiency curve of my PSU. You can see it's most efficient between around 40-60%. So if you get a 1000W PSU and on average you're using 500W then that's pretty good. If you're only using 300W though then you should probably get a lower wattage PSU.


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## Pictus (Mar 30, 2020)

vitocorleone123 said:


> Don't get a massive wattage PSU unless you need it - you'll be paying more for electricity. Do get Gold or Platinum rated. Do get something that's silent up until at least ~250 watts or so, which usually means a 650 - 1000 watt PSU.



Not true...


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## Technostica (Mar 30, 2020)

You need to look at your own hardware and your workflow to see how many watts you average at idle, when doing basic tasks and when you are running a demanding load by your standards.
This can be miles away from what these benchmarks tools consume.
My system tends to consume between 50 and 100 watts AC so the PSU is outputting less than 90W DC.
Power supplies are rated by their DC output not their AC input.
Keep that in mind otherwise you might over specify by even more than intended.


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## vitocorleone123 (Mar 30, 2020)

Yes, yes. If you want to dive into details, which not everyone does. I was trying to keep it simple, which is a good rule of thumb. I should've said as much in my post, admittedly.


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## kitekrazy (Apr 5, 2020)

They only things that are power hogs are often a CPU and video card. If you are not a gamer 650 should give you plenty of overhead.


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