Question Whats the safe watt range for my power supply?

May 31, 2020
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Is it better having the wattage amount from my components to be equal as the wattage amount my power supply reaches, or is it better to leave the power supply with few non-used watts or can I have few more watts than what my power supply max wattage range can have
 

helper800

Distinguished
Is it better having the exact same watage amount from my components to be equal as the wattage amount my power supply reaches, or is it better to leave the power supply with few non-used watts or can I have few more watts than what my power supply max wattage range can have
PSU's are most efficient at 40-70% usage of their wattage. Running a computer with 550w usage with a 550w PSU is possible but highly unsustainable for the long term for the PSU. Even if you did do the above example you would have to buy a very nice PSU and that still might cause problems. Personally when I am buying a PSU I look at the wattage requirement on pcpartpicker and get a PSU that is 200 watts higher capacity. This ensures that you will not be redlining a PSU while using it and puts it close to or inside of that efficiency curve I mentioned above.

For instance something like this as an example would not be unreasonable: https://pcpartpicker.com/list/nf88wz
 

hang-the-9

Titan
Moderator
Is it better having the wattage amount from my components to be equal as the wattage amount my power supply reaches, or is it better to leave the power supply with few non-used watts or can I have few more watts than what my power supply max wattage range can have
You always want to have a higher wattage PSU than the max number needed for the system, plus the quality of the PSU makes a big difference here. A cheap 750 watt PSU often will not deliver anywhere near that for example, some units just plain lie about their capability.

Keep about a 25%-30% headroom in the PSU or more if at all possible, if you need 300, get a 400. If you need 700 for the system then you are in the 1,000 rante.
 

Eximo

Titan
Ambassador
Points above summarized

  1. Efficiency - slight savings in electricity by running between 40-70% (or 50-80%) total load.
  2. Efficiency ratings. 80+, Bronze, Gold, Platinum, Titanium (You don't see Silver much anymore) Better the rating the more efficient the power supply is. Higher efficiency typically means higher quality and a longer warranty period.
  3. Bigger is always better, to a point. with the efficiency in mind, you don't want a 1000W supply for a 200W load.
  4. Noise - Closer you are to the power rating on a power supply, the more likely the fan will spin fast and be loud (Some power supplies have a passive mode as well)
  5. Power supplies slowly degrade over time and are capable of less of their maximum output, so going a little large means longer time in the 'good range'
 
Last edited:

hotaru.hino

Commendable
Sep 1, 2020
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Another reason to have some headroom: CPUs and GPUs may exceed their TDP/TBP ratings in short bursts. It's probably not a good idea to have say a PSU running at 90% capacity encountering these spikes constantly.
 
Good summary from Eximo ^^

I might add that quality counts, perhaps even most of all.
A cheap unit might be rated at room temperature which is not realistic.
Better units are rated at 50c. which you might see in a case.

Also, higher quality units can actually deliver more power than their ratings.
 
May 31, 2020
18
0
10
0
You always want to have a higher wattage PSU than the max number needed for the system, plus the quality of the PSU makes a big difference here. A cheap 750 watt PSU often will not deliver anywhere near that for example, some units just plain lie about their capability.

Keep about a 25%-30% headroom in the PSU or more if at all possible, if you need 300, get a 400. If you need 700 for the system then you are in the 1,000 rante.
Thanks
 

mxnty

Great
Mar 4, 2021
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Great job explaining above to everyone ^^
Your components draw power, not that your PSU feeds power, it only gives how much is drawn. As an (somewhat unorthodox) example, if you go to the the theater and ask for a ticket, they’ll give you one ticket, even if they have 2. Yes this was odd, but essentially components ask, PSU gives, it doesn’t give if it isn’t asked.
 
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