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Thread: What is the most important thing to look at in a PSU

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    Default What is the most important thing to look at in a PSU

    So I've been doing some research on power supplies for a while though there are many things I still don't understand. If you know the answer to this questions can you answer them as thoroughly as possible? If not, you can just tell me where to find that info it would be appreciated thanks.

    1.- WATTAGE:

    I've seen many people saying "this systems pulls this wattage, overclocked it pulls that wattage" I wonder how you get to that number, when there are no reviews or power consumption figures for certain components.

    In this case there do exist reviews to I take roughly 168W from the i7 8700K overclocked to 5 GHz using 1.28V

    https://www.tomshardware.com/reviews...u,5252-12.html

    and 322W from an MSI lightning Z GPU pushed to the max.

    https://www.techpowerup.com/reviews/...ning_Z/27.html

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    That gives us a total of 490W, I KNOW THIS IS PRETTY MUCH AN UNREALISTIC case scenario. 99% of the time if not all the time your components aren't loaded to 100% but I know some AVX workloads draw a significant amount of power and overestimating is better than underestimating.

    Now I've seen people saying a 550W power supply (A GOOD QUALITY ONE OF COURSE) will suffice but this is already 490W and since most of this is 12V I estimate like 40A on that rail only for CPU and GPU

    CORRECT ME IF I AM WRONG, IF SO what is the best method to find out what is the right wattage for a certain part config even when you have really no idea about what X or W component consumes.

    __________________________________________________ __________________________________________________ __________________________________________________ ____________


    I know there are kill-a-watt units and some corsair PSUs tell you how much power the system is drawing but of course you can't use those if you don't have a PC yet.

    Besides AFAIK THEY CANNOT ACCURATELY measure power spikes OR CAN THEY? Please let me know. Should I really be concerned by those power spikes? To my understanding if the system pulls more current or wattage than the PSU is set to deliever the PSU will turn off or just burn in case of cheap units, REGARDLESS of for how long you exceed the PSU's limit or am I making a mistake?

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    2.- HOW MUCH QUALITY AND PROTECTIONS IS ENOUGH?

    I mean, when a super high-end power supply is too much or when a budget unit like the EVGA 450BT or corsair CX450 is too little?

    I guess IT DEPENDS on how safe you want to be and also the quality of electricity on your contry/region but I wanted a much more thorough answer.

    So how do you justify buying something like a seasonic PRIME titanium 600-650W for a home theather PC. Besides higher efficiency, lower noise and that bunch of things. IS IT WORTH IT to spend that much for peace of mind?

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    3.- WHAT SHOULD YOU LOOK AT FIRST IN A PSU?

    So there are a ton of things that determine how good a PSU is, working protection features, soldering quality, the capacitors use, the fan bearing type (and the model itself I suppose) ripple, hold-up time and much more.

    But some aspects must be more essential than others, AND AGAIN I'M GOING TO SAY IT DEPENS? But it depends on what?


    __________________________________________________ __________________________________________________ __________________________________________________ ____________

    If there is any difference in what features matter the most between a SMPS for a basic computer, a gaming computer, a workstation computer and a server one? Or this isn't even relevant?

    How much ripple/voltage regulation is OK, or it doesn't matter at all providing they are within spec. If so, I wonder why bother testing it? What do you find crucial to be adressed in a PSU review? You can add any relevant information in case I forgot anything.

    __________________________________________________ __________________________________________________ __________________________________________________ ____________


    Sorry if these are TOO MANY QUESTIONS but again any article, book, etc is welcome thank you in advance.
    Last edited by COFASA; 06-05-2018 at 10:15 PM. Reason: Too overwhelming, I needed to separate text better

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    1. Wattage is irrelevant, as long as its enough. If you have enough, anything else makes little sense.
    2. You want as much as you can get. If possible Multi Rail and OTP for Protections, working of course and as close to the rated wattage as possible. As well as quality, you want as much as possible. But you have to believe the manufacturer for that...
    3. (Fan) Noise, Price, what you get in the Box, Cables, types and amount (of connectors), size. Many things.


    Differences aren't that small, obviously...

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    Quote Originally Posted by Stefan Payne View Post
    1. Wattage is irrelevant, as long as its enough. If you have enough, anything else makes little sense.
    2. You want as much as you can get. If possible Multi Rail and OTP for Protections, working of course and as close to the rated wattage as possible. As well as quality, you want as much as possible. But you have to believe the manufacturer for that...
    3. (Fan) Noise, Price, what you get in the Box, Cables, types and amount (of connectors), size. Many things.


    Differences aren't that small, obviously...
    thank you

    1.- OK I get that, but how do you determine it is enough wattage? That is what drives me mad, they usually don't point out how they calculate that a system draws a certain amout of power. Also what about room to upgrade? I know the trending is to have more efficienct pars but what if I want to overclock later or add more drives, etc.

    2.- Well so at what point you can skimp on a PSU if you "can't get" something better? Is there any line you shouldn't cross when purchasing chip stuff? Like the bare minium of protections you should have, etc. I know it depends but again long answer is fine for me

    3.- OK yea but what is the key feature or features amidst all those things?

    4.- Yes, I know, but give at least some examples

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    Quote Originally Posted by COFASA View Post
    thank you

    1.- OK I get that, but how do you determine it is enough wattage? That is what drives me mad, they usually don't point out how they calculate that a system draws a certain amout of power. Also what about room to upgrade? I know the trending is to have more efficienct pars but what if I want to overclock later or add more drives, etc.
    You go through and read reviews CPU/GPU, Tomshardware and Gamersnexus are both good with their data as they measure via EPS/PCIe

    Quote Originally Posted by COFASA View Post
    2.- Well so at what point you can skimp on a PSU if you "can't get" something better? Is there any line you shouldn't cross when purchasing chip stuff? Like the bare minium of protections you should have, etc. I know it depends but again long answer is fine for me
    I (personally) generally recommend going with a CX/m grey label, Masterwatt, Pure Power 10 or Performance A+ as the minimum, but exceptions do apply.
    Just some nerd from 'Straya

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    Quote Originally Posted by awesomegamer919 View Post
    You go through and read reviews CPU/GPU, Tomshardware and Gamersnexus are both good with their data as they measure via EPS/PCIe



    I (personally) generally recommend going with a CX/m grey label, Masterwatt, Pure Power 10 or Performance A+ as the minimum, but exceptions do apply.
    Interesting, yeah I used tomshw as a reference because of that, it takes into account power spikes right?

    But like I said according to tomshaw 8700K OC'ed + MSI 1080 ti gaming Z that is 490W of power just for the CPU and GPU and people say that 550W is more than enough

    Exceptions?

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    For me one of the most important things cannot be seen, namely that when failing it does not cause collateral damage.

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    Quote Originally Posted by COFASA View Post
    Interesting, yeah I used tomshw as a reference because of that, it takes into account power spikes right?
    Generally you should focus more on continuous power than spikes.

    Quote Originally Posted by COFASA View Post
    But like I said according to tomshaw 8700K OC'ed + MSI 1080 ti gaming Z that is 490W of power just for the CPU and GPU and people say that 550W is more than enough
    That's because the CPU+GPU are >90% of a system's total wattage.

    Quote Originally Posted by COFASA View Post
    Exceptions?
    Not everyone has access to all those units so sometimes you end up with an S12II/M12II or other SI level PSUs as the only option.
    Just some nerd from 'Straya

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    Quote Originally Posted by awesomegamer919 View Post
    Generally you should focus more on continuous power than spikes.



    That's because the CPU+GPU are >90% of a system's total wattage.



    Not everyone has access to all those units so sometimes you end up with an S12II/M12II or other SI level PSUs as the only option.
    So, if certain components peak at 600W of wattage and the PSU is 500W it doesn't matter? Spikes for a short period of time do not cause any issues.

    SI level?

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    Quote Originally Posted by COFASA View Post
    So, if certain components peak at 600W of wattage and the PSU is 500W it doesn't matter? Spikes for a short period of time do not cause any issues.
    If your system is spiking to 600w and you only have a 500w PSU then there's something wrong, even the most volatile 1080Tis only spike 50-70w and CPUs barely spike at all... Also, you should be leaving at least a little headroom - a 550w PSU that occasionally has <50ms spikes to 600w would be fine.

    Quote Originally Posted by COFASA View Post
    SI level?
    System integrator - Corsair VS/BeQuiet System Power/EVGA B1/S12II etc...
    Just some nerd from 'Straya

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    Quote Originally Posted by awesomegamer919 View Post
    If your system is spiking to 600w and you only have a 500w PSU then there's something wrong, even the most volatile 1080Tis only spike 50-70w and CPUs barely spike at all... Also, you should be leaving at least a little headroom - a 550w PSU that occasionally has <50ms spikes to 600w would be fine.



    System integrator - Corsair VS/BeQuiet System Power/EVGA B1/S12II etc...
    thanks

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