Question What size PSU do people actually need?

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thinkwired

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Consider these 5 different pieces of advice/scenarios.

Lets suppose we are building a rig with an i5 -10400 and a 1660 super.

  1. Pcpartpicker lays out a configuration they recommend with a 600w power supply even though they say the consumption will be 274w.
  2. The graphics card producer will tell you that they recommend a 450w PSU.
  3. Any knowledgeable PSU guy on this forum will tell you that you need at least a 550w power supply.
  4. The PSU calculator on this site suggests says I need something that will cover 340-ish watts.
  5. Dell, HP, and the likes will put proprietary PSU's in configurations like this with UNDER 450w.
Given that, how does anyone know what size PSU they really need? Don't forget to confuse things even more with the fact that some high quality PSU's deliver steadier power with a lower wattage rating than a bad unit with a higher rating (example, a great 500w vs a bad 550w). How are we suppose to reconcile what is truly needed? How on earth do pre builts function with less wattage than is recommended to power their components?

Discuss.
 

Prad_Bitt

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What I think is

You can use PS calculators to get a load wattage. That load wattage has to be calculated as the minimum power a PSU can supply at 100% load after accounting for its efficiency. For example I have an RM650. Corsair says 90% efficiency at 100% load (I don't know the exact number, just for math's sake) which means it can supply a max of 595W while drawing 650W from the wall. So I can have components drawing 595W max

A lot of people buy bigger PSUs because not all chips take the same power, I've seen faulty power hungry cards with my friend, and I've seen 2060 supers working on trash 550w PSUs with a 3600. Although that isn't pushing it much.

Quality of the PSU has a lot to do with reliability and longevity, I believe. Which is why I go for quality units whatever wattage they may be.

Nvidia as far as I know, used a 9900K + whatever GPU to recommend a PSU for the 20 series cards. So obviously if you use a R3 3100 you'll have lower wattage needs. It also depends on OC models etc.

I don't know the specifics about quality, but I do know that I'd pick a quality 500W over a trash 550W any day. I think it has something to do with how much load it can take on 12V and capacitors and stuff man idk that much I'm no engineer.

Prebuilts function like that because you're not supposed to "upgrade" Prebuilts by yourself. It is literally on the edge, and if you swap in anything more powerful you risk your system

That being said, for an i5-10400 + 1660 Super id say take a Corsair CX550. It's much superior quality than a lot of PSUs (it's B Tier, A is best, B is second). 550 also gives you a lot of headroom to upgrade. For example you can probably squeeze a 2060 Super in that. But for the bare minimum, a CX450 will do, because why risk it? You can probably get away with even a 400W trash quality PSU but why risk it? It's giving you the peace of mind and ability to sleep like a baby at night knowing your PC isn't gonna explode into your face
 
Reactions: MeanMachine41
Rules for selecting the right PSU are:

  1. Don't go cheap
  2. Get a gold certified (or better) unit from a reputable manufacturer.
  3. PSU configurators suck so calculate based on each hardware wattage requirement then add 20%.
  4. Seek a review of the PSU from a site preferably from jonnyguru.
The PSU is the most important hardware component in your system and not to be underestimated.
 
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Prad_Bitt

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Rules for selecting the right PSU are:

  1. Don't go cheap
  2. Get a gold certified (or better) unit from a reputable manufacturer.
  3. PSU configurators suck so calculate based on each hardware wattage requirement then add 20%.
  4. Seek a review of the PSU from a site preferably from jonnyguru.
The PSU is the most important hardware component in your system and not to be underestimated.
Yes, Jonny guru is an internet PSU God. He has a list of Corsair PSUs, ranking them quality wise. If you want Corsair psu you can check out his list. He works there now too lol
 

DSzymborski

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Consider these 5 different pieces of advice/scenarios.

Lets suppose we are building a rig with an i5 -10400 and a 1660 super.

  1. Pcpartpicker lays out a configuration they recommend with a 600w power supply even though they say the consumption will be 274w.
  2. The graphics card producer will tell you that they recommend a 450w PSU.
  3. Any knowledgeable PSU guy on this forum will tell you that you need at least a 550w power supply.
  4. The PSU calculator on this site suggests says I need something that will cover 340-ish watts.
  5. Dell, HP, and the likes will put proprietary PSU's in configurations like this with UNDER 450w.
Given that, how does anyone know what size PSU they really need?
Add up the components, add a 30% margin for long-term stability and life of your parts.

Don't forget to confuse things even more with the fact that some high quality PSU's deliver steadier power with a lower wattage rating than a bad unit with a higher rating (example, a great 500w vs a bad 550w). How are we suppose to reconcile what is truly needed?

Not sure how this is confusing. Is it confusing that you don't rank car purchases solely by top speed? Rate houses solely by square footage? Rate restaurants solely by the amount of food given? The basic problem is that you appear to think that the only thing separating PSUs is the amount of their rated output.

How on earth do pre builts function with less wattage than is recommended to power their components?
Again, you're thinking very one-dimensionally. There are far more questions than does it run right now?.

Dell or HP don't particularly care about the long-term health of your components; they only care about your stuff for a year or two, the window during which they have to replace anything that fails. They make money selling you replacements.

The GPU manufacturers care a bit more because they have to replace that card for typically three years. But they're not that concerned with your rig having a long life otherwise.

While hobbyists, we give recommendations for PCs to have long lives, to run cool and efficiently, and fulfill all the needs of other hobbyists. HP doesn't care if your FartPower RGB 500W fries your motherboard in three years. We do.
 
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Prad_Bitt

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Add up the components, add a 30% margin for long-term stability and life of your parts.




Not sure how this is confusing. Is it confusing that you don't rank car purchases solely by top speed? Rate houses solely by square footage? Rate restaurants solely by the amount of food given? The basic problem is that you appear to think that the only thing separating PSUs is the amount of their rated output.



Again, you're thinking very one-dimensionally. There are far more questions than does it run right now?.

Dell or HP don't particularly care about the long-term health of your components; they only care about your stuff for a year or two, the window during which they have to replace anything that fails. They make money selling you replacements.

The GPU manufacturers care a bit more because they have to replace that card for typically three years. But they're not that concerned with your rig having a long life otherwise.

While hobbyists, we give recommendations for PCs to have long lives, to run cool and efficiently, and fulfill all the needs of other hobbyists. HP doesn't care if your FartPower RGB 500W fries your motherboard in three years. We do.
Human eye can't see over 500W anyway it can only see RGB. How dare you ruin the name of HP.
 
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thinkwired

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Not sure how this is confusing.
Its confusing because the average user can't discern what is a good PSU and what is a bad one, heck, knowledgeable people on this site don't 100% agree. You think Mom, Dad, or Nana understand what Japanese capacitors are? I doubt it yet, Nana will buy her grandson a PSU this xmas.

Is it confusing that you don't rank car purchases solely by top speed? Rate houses solely by square footage? Rate restaurants solely by the amount of food given?
A cars sole job isn't to deliver top speed. A PSU's sole job is to deliver clean safe power at its rating.

The basic problem is that you appear to think that the only thing separating PSUs is the amount of their rated output.
I don't think that. What I think know is that I gave 5 decent examples of how the internet can easily confuse the average person in the market for a PSU.

Dell or HP don't particularly care about the long-term health of your components; they only care about your stuff for a year or two, the window during which they have to replace anything that fails. They make money selling you replacements.
A year or two?

I hear this argument a lot but, I personally have had 2 HP computers that gave 10 years of service before being retired. They did not die. Neither did the prebuilts I bought for my parents. I don't doubt that all kinds of computers give up the ghost sometimes but, more often than not, I see ancient prebuilts in peoples houses chugging away. Maybe its just me and my evidence is anecdotal but, I see absolute dinosaurs all the time. Am I the only one?

BTW, I'm less concerned with the quality, my point is that they are seemingly under-powered. Shouldn't it be worse that they are FartPower 300w when the GPU calls for at least 450w? How do they run?
 
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