Question Guide to buy a proper SMPS/PSU

Jul 16, 2022
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8
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I'm planning to build a pc. I want to know:

If there is any problem using a higher or lower wattage SMPS for a Custom PC.

In what basis should I determine a good SMPS for my PC.

What are the possible problems that can be caused if buying a cheap PSU.
 

DSzymborski

Titan
Moderator
- The wattage you choose depends on what your components are. No point to shelling out for an 850W PSU when, for example, your PC may only peak at 250W. PSUs only draw the power they need from the wall.

- Both output and quality of the unit. There are a lot of PSU reviews here on the main page and, for the inexperience, there are a number of PSU tier list threads available on the web, including a stickied one in our Power Supplies forum. Consumer "reviews" at websites have zero value as you can only truly properly review a PSU with very specialized equipment and knowledge.

- A cheap PSU may cause your PC to turn off at load or even less-than-a-full-load, a cheap PSU may shorten the lives of all the components connected to it, a cheap PSU may cause the components to suddenly fail, and a cheap PSU, in some cases, can cause a fire.

IMG_2131.thumb.jpeg.9e7cff1bac505eb5f16545389b6e5756.jpeg
 
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Jul 16, 2022
97
8
35
- The wattage you choose depends on what your components are. No point to shelling out for an 850W PSU when, for example, your PC may only peak at 250W. PSUs only draw the power they need from the wall.

- Both output and quality of the unit. There are a lot of PSU reviews here on the main page and, for the inexperience, there are a number of PSU tier list threads available on the web, including a stickied one in our Power Supplies forum. Consumer "reviews" at websites have zero value as you can only truly properly review a PSU with very specialized equipment and knowledge.

- A cheap PSU may cause your PC to turn off at load or even less-than-a-full-load, a cheap PSU may shorten the lives of all the components connected to it, a cheap PSU may cause the components to suddenly fail, and a cheap PSU, in some cases, can cause a fire.

IMG_2131.thumb.jpeg.9e7cff1bac505eb5f16545389b6e5756.jpeg
So let's say I build a pc with these specs:

CPU- i3 12100
M.Board- MSI Pro H610M G
RAM- Corsair LPX 8gb DDR3 3200mhz
ROM- 1tb SeaGate Barracuda

What PSU should I use
 
Jul 16, 2022
97
8
35
The power you need will largely be determined by your graphics card.
Here is a handy chart:
http://www.realhardtechx.com/index_archivos/Page362.htm
If your psu is too weak, parts may not run well, and sometimes not at all.

I have no problem overprovisioning a PSU a bit. Say by 20%.
It will allow for a stronger future graphics card upgrade.
It will run cooler and quieter.
Modern graphics cards can have high power demand spikes that need to be handled.
A PSU will only use the wattage demanded of it, regardless of it's max capability.

Not knowing anything about a particular psu, look at the warranty.
If it is for 7 to 10 years or more, you will likely get a quality unit.

DO NOT buy a cheap psu.

A cheap PSU will be made of substandard components. It may not have all safety and overload protections.
The danger is if it fails under load, it can destroy anything it is connected to.
It will deliver advertised power only at room temperatures, not at higher temperatures found when installed in a case.
The wattage will be delivered on the 3 and 5v rails, not on the 12v rails where modern parts
like the CPU and Graphics cards need it. What power is delivered may fluctuate and cause instability;
issues that are hard to diagnose.
The fan will need to spin up higher to cool it, making it noisy.
A cheap PSU can become very expensive.

Do not buy one.
 
Jul 16, 2022
97
8
35
The power you need will largely be determined by your graphics card.
Here is a handy chart:
http://www.realhardtechx.com/index_archivos/Page362.htm
If your psu is too weak, parts may not run well, and sometimes not at all.

I have no problem overprovisioning a PSU a bit. Say by 20%.
It will allow for a stronger future graphics card upgrade.
It will run cooler and quieter.
Modern graphics cards can have high power demand spikes that need to be handled.
A PSU will only use the wattage demanded of it, regardless of it's max capability.

Not knowing anything about a particular psu, look at the warranty.
If it is for 7 to 10 years or more, you will likely get a quality unit.

DO NOT buy a cheap psu.

A cheap PSU will be made of substandard components. It may not have all safety and overload protections.
The danger is if it fails under load, it can destroy anything it is connected to.
It will deliver advertised power only at room temperatures, not at higher temperatures found when installed in a case.
The wattage will be delivered on the 3 and 5v rails, not on the 12v rails where modern parts
like the CPU and Graphics cards need it. What power is delivered may fluctuate and cause instability;
issues that are hard to diagnose.
The fan will need to spin up higher to cool it, making it noisy.
A cheap PSU can become very expensive.

Do not buy one.
Oh okok... Thanks for clearing my doubts...
😊❤️
 
Jul 16, 2022
97
8
35
The power you need will largely be determined by your graphics card.
Here is a handy chart:
http://www.realhardtechx.com/index_archivos/Page362.htm
If your psu is too weak, parts may not run well, and sometimes not at all.

I have no problem overprovisioning a PSU a bit. Say by 20%.
It will allow for a stronger future graphics card upgrade.
It will run cooler and quieter.
Modern graphics cards can have high power demand spikes that need to be handled.
A PSU will only use the wattage demanded of it, regardless of it's max capability.

Not knowing anything about a particular psu, look at the warranty.
If it is for 7 to 10 years or more, you will likely get a quality unit.

DO NOT buy a cheap psu.

A cheap PSU will be made of substandard components. It may not have all safety and overload protections.
The danger is if it fails under load, it can destroy anything it is connected to.
It will deliver advertised power only at room temperatures, not at higher temperatures found when installed in a case.
The wattage will be delivered on the 3 and 5v rails, not on the 12v rails where modern parts
like the CPU and Graphics cards need it. What power is delivered may fluctuate and cause instability;
issues that are hard to diagnose.
The fan will need to spin up higher to cool it, making it noisy.
A cheap PSU can become very expensive.

Do not buy one.
So by the chart and your answers, I should determine my psu based on its quality of long life and the GPU in my pc or the GPU I will be going to buy...

Correct ..?
 
So by the chart and your answers, I should determine my psu based on its quality of long life and the GPU in my pc or the GPU I will be going to buy...

Correct ..?
Probably correct.
Unless you will have a strong processor and are indulging in overclocking, more power might be appropriate.
One of the most common upgrades will be to a stronger graphics card.
Keep in mind what upgrade may be possible.
Overly strong is OK.
Just do not go crazy.

Also, some cases may have requirements for SFX size as well as ATX length limits.
Check on those.

Seasonic focus and corsair rm are two popular quality units.
 
Jul 16, 2022
97
8
35
Probably correct.
Unless you will have a strong processor and are indulging in overclocking, more power might be appropriate.
One of the most common upgrades will be to a stronger graphics card.
Keep in mind what upgrade may be possible.
Overly strong is OK.
Just do not go crazy.

Also, some cases may have requirements for SFX size as well as ATX length limits.
Check on those.

Seasonic focus and corsair rm are two popular quality units.
Thank you a lot for your help... It has really helped me gain knowledge.. And I'm clear on how to buy a psu for my pc... Thanks once again
 

Karadjgne

Titan
Ambassador
Ever eaten at a 'good quality' resteraunt where the price was expensive and the food was ok, but nothing special? Or how about a little mom&pop stand on the corner where the food was really 'good quality' but the price was cheap? A lot depends on the definition of 'good quality'.

A tell-tale marker of a good quality psu is its warranty. It tells you right away just how much faith the company has in its unit. Another marker is the gpu connections, a good quality unit will have close to its rated power, 6pin is 75w, 6+2pin is 150w so if a 550w has 1x 6pin, it's junk.

12v rail is another marker, it should be right up there with the claimed rated power, so a 550w should have @ 520w or more.

The better quality units will have all those markers, plus have a whole heap of protective circuits, OCP, OTP, OVP, UVP, SC etc.

Wattage or 80+ rating is never a marker. I would trust a Gold rated Corsair 550w Rmx to deliver 550w continuously for years straight, before I'd ever trust a 1000w Aerocool Platinum to deliver the same wattage for the same time span.

Whatever unit you look for, Google reviews for it, professional reviews, not Amazon crap. Read the conclusions. If they have recommendations for or against, pro's or cons, take notice of those. If in doubt still, then ask. Finding something decent isn't hard, finding something decent that's within budget and makes sense, that's much harder.
 
Jul 16, 2022
97
8
35
Ever eaten at a 'good quality' resteraunt where the price was expensive and the food was ok, but nothing special? Or how about a little mom&pop stand on the corner where the food was really 'good quality' but the price was cheap? A lot depends on the definition of 'good quality'.

A tell-tale marker of a good quality psu is its warranty. It tells you right away just how much faith the company has in its unit. Another marker is the gpu connections, a good quality unit will have close to its rated power, 6pin is 75w, 6+2pin is 150w so if a 550w has 1x 6pin, it's junk.

12v rail is another marker, it should be right up there with the claimed rated power, so a 550w should have @ 520w or more.

The better quality units will have all those markers, plus have a whole heap of protective circuits, OCP, OTP, OVP, UVP, SC etc.

Wattage or 80+ rating is never a marker. I would trust a Gold rated Corsair 550w Rmx to deliver 550w continuously for years straight, before I'd ever trust a 1000w Aerocool Platinum to deliver the same wattage for the same time span.

Whatever unit you look for, Google reviews for it, professional reviews, not Amazon crap. Read the conclusions. If they have recommendations for or against, pro's or cons, take notice of those. If in doubt still, then ask. Finding something decent isn't hard, finding something decent that's within budget and makes sense, that's much harder.
Ohhhhh... Okok... That's very detailed... Thanks a lot... 👍