1. Welcome to the eTeknix Forums Guest. Please register or login and remember to read the forum guidelines to make your stay as pleasant as can be.

How to choose a power supply?

Discussion in 'General Hardware' started by Indloon, May 11, 2013.

  1. Indloon

    Indloon Member

    Joined:
    Apr 4, 2013
    Messages:
    47
    Likes Received:
    5
    Location:
    Tallinn, Estonia
    Show PC Specs
    CPU:
    Intel Celeron @2.4GHz
    Memory (RAM):
    A-Data 512mb ( 2x256mb )
    Storage:
    Samsung HDD 40GB
    Graphics Card(s):
    HIS Radeon HD 9250
    Power Supply (PSU):
    CodeGen 350W
    Monitor(s):
    Samsung SyncMaster T22A300
    Operating System(s):
    Windows XP SP3 32-bit
    This is a basic overview of what to know about choosing a power supply!
    ( Note, my English language is not the best, so there are probably some mistakes ... )
    But that shouldn't stop you enjoying this!

    1. Look at watts

    The most important parameter ( and I can say that, it's the only thing what most consumers know ) is the maximum power provided by the power supply, what shows how much energy can power supply provide to a computer. However, there is a little trick here - cheap power supply companies proudly show their power supplies Peak Wattage - on maximum load, it will probably blow up in a minute.
    Then again quality power supply companies show their power supplies Continues Wattage, what is often 20-30% below the peak wattage. And in addition power supply power is divided into different voltage rails - 12V, 5V and 3,3V. Every voltage has it's own maximum amps and from physics, it's voltage x amps = watt. Quality power supply companies provide a scheme for every rail.


    2. Efficiency is important

    In addition, it is also important power supply efficiency, in other words, how much from consumed power is useful and how much is in loss ( heat,etc ). My current PC has a cheap 350W power supply what doesn't have no efficiency tag and I used watt-meter last week and it takes about 762W under full load. ( I will buy a Seasonic G-series 550W PSU soon to replace that cheap disaster ) Quality power supplies always show that information on their products, cheap power supply companies don't provide that information at all.

    80 PLUS ( known also as 80 Plus or 80+ ), it's certification program, what was started in 2004 year by Ecos Consulting and EPRI ( Electric Power Research Institute ) and that shows power supply power consume efficiency. These power supplies what ensure 80% or better efficiency under 20%, 50%, 100% load and what power factor is 0.9 or better under 100% load get 80 PLUS tag. 80 PLUS has five higher categories - Bronze, Silver, Gold, Platinum and Titanium ( Titanium needs under 50% load 96% of efficiency ). So whenever you decide to buy a new power supply, look for 80+ Bronze power supplies if you are on budget, if you have extra 20 bucks, get 80+ Gold!

    There is also something called PFC ( Power Factor Correction ), it is a method used on power supplies, which reduces the reactive power consumed - there is either passive or active form ( Passive and Active PFC ). In the European Union all power supplies must be equipped with PFC.


    3. Which manufacturer's power supply to choose?

    There are a lot of power supply providers, but there are only some real manufactures ( corresponds to F1, where for example, Ferrari manufactures engines to most of teams ). And in power supplies, Ferrari is Seasonic.
    However, there is a large number of so-called OEM manufacturers, who use different manufactures content, but they build case around it. If the content is good, then the power supply is good - for example Corsair, Antec and others. But if you look for a cheap power supply, you will get a cheap power supply and probably PC components will burn down.

    You can check who build manufactures power supplies here - http://www.tomshardware.com/reviews/psu-manufacturer-oem,2729.html


    4. How powerful power supply do I need?

    For that, you need to know how much power does your computer need, but that number is not constant - if the computer is idle or you do simple work such as browsing web pages, then your computer's power consumption is very low. But when you watch Full HD movie or play modern 3D-game, power consumption flies into space.

    So choosing a power supply, you have to known the maximum power consumption of your computer ( generally there are rare situations where absolutely all components are under 100% load and because of that it's used 90% to measure computer maximum power ). To make it easier for you, there is a useful web application called eXtreme Power Supply Calculator Lite, what you can find here - http://www.extreme.outervision.com/psucalculatorlite.jsp .Choose the components from the list and hit the "Calculate" button! Specialists always recommend to choose at least 25-30% of extra capacity of power. So if your computer uses 300W, then you should get at least a quality power supply with 375W.


    5. Are all cables there?

    The most common problem with cheap power supplies is that there aren't enough cables for your computer. Older power supplies have 20-pin cable for motherboard, but newer motherboards need 24-pin cable. Also older motherboards need 4-pin cable for CPU, but modern motherboards need 8-pin cable for CPU. Powerful video cards need two 8-pins cables - cheap ones usually don't even have a 8-pin cable!

    Most of quality power supplies are usually modular - attached are minimum number of cables, usually there is only 24-pin cable attached for motherboard, these power supplies are semi-modular. When you choose a power supply, always try to go with modular or at least a semi-modular power supply, it will look better and the cables won't block airflow in your case!


    6. Rails.. What are they, exactly?

    Part of the venom towards multi-rail PSU’s stems from a completely incorrect assessment of what multi-rail actually means. Multi-rail PSU’s DO NOT use any more power sources than their single-rail counterparts. In fact, almost all PSU’s, with the exception of some extremely high wattage units, only use one.
    It all comes down to a little thing that protects your system from overvoltage and potential computer bonfires: OCP. OCP is Over Current Protection. OCP will monitor your +12v power source output for current surges, spikes or simply too much current that could end up causing damage to your components. There is OCP present on the other PSU rails too, but we’re not talking about those.
    So what is a single-rail power supply? Put simply, the entirety of the +12v power source is monitored on a single circuit, monitored by an OCP chip configured to shut off if the power supply’s max Amperage is reached.
    In contrast, a multi-rail PSU has multiple (2+) monitoring channels on the +12v power source, each with a separate Amperage rating which is a division of the PSU’s maximum rated output (plus perhaps some additional headroom to prevent shutdowns from reaching the top-end) . Some rails are dedicated to different things, so you’ll have higher-rated monitoring channels for PCI-E connections and CPU power, along with lower-rated ones for hard drives and such.
    So there you have it. Is the power cleaner on either? No. They’re the same power source. Does it affect ripple or electrical noise? Not really, at least, not significantly enough for it to matter to .. anyone.

    Which is better?

    The answer, simply, is neither. They’re effectively the same in the way they deliver power to your components.
    There is however a benefit that one of them offers over the other: safety. For low wattage units this doesn’t matter, as the max Amperage will be triggered on either single-rail or multi-rail PSUs in the event of an overload. However, as you reach higher wattage units, you’ll find that it’s very difficult to hit the max Amperage of the PSU on a single-rail unit. Chances are in the event of an overload on the +12V power source, it’s going to potentially burn your components or itself before OCP kicks in. In this scenario, multi-rail PSU’s are better simply because each rail has a lower Amperage rating that is a portion of the power supply’s maximum. It’ll make the OCP easier to trigger, and therefore, more likely to save your components from harm.



    Indloon
     
  2. Zobator

    Zobator Well-Known Member

    Joined:
    Mar 29, 2013
    Messages:
    709
    Likes Received:
    46
    Location:
    Hasselt, Belgium
    Show PC Specs
    CPU:
    Intel(R) Pentium(R) Dual-Core CPU E5500 @ 2.80GHz
    Graphics Card(s):
    ATI Radeon HD 4650 512MB
    Operating System(s):
    Windows 7 Home Premium 64 bits
    Very interesting to read! Thanks! :)
     
  3. TheWOLF26

    TheWOLF26 Forum Mod

    Joined:
    Jun 29, 2011
    Messages:
    1,055
    Likes Received:
    35
    Location:
    Romania
    Show PC Specs
    CPU:
    Intel core I7 2600K 3.4Ghz with custom made watercooling
    Motherboard:
    ASUS P8P67 REV 3
    Memory (RAM):
    Kingston HyperX Savage 8GB(2x4GB), DDR3, 1600MHz, CL9, 1.5V, XMP
    Storage:
    WD Caviar Blue 1TB SATA3 6GB/s
    Graphics Card(s):
    EVGA GTX 680 Classified 4GB
    Power Supply (PSU):
    Corsair GS800
    Case:
    An MSI old case(a very HARD case)
    Monitor(s):
    ASUS VH222D 22" 1920x1080
    Operating System(s):
    WINDOWS 7 ULTIMATE 64 bit
    Internet Connection:
    Broadband 1000mb/s
    Interesting guide. I made it sticky for a quick access for everyone :)
     
  4. Indloon

    Indloon Member

    Joined:
    Apr 4, 2013
    Messages:
    47
    Likes Received:
    5
    Location:
    Tallinn, Estonia
    Show PC Specs
    CPU:
    Intel Celeron @2.4GHz
    Memory (RAM):
    A-Data 512mb ( 2x256mb )
    Storage:
    Samsung HDD 40GB
    Graphics Card(s):
    HIS Radeon HD 9250
    Power Supply (PSU):
    CodeGen 350W
    Monitor(s):
    Samsung SyncMaster T22A300
    Operating System(s):
    Windows XP SP3 32-bit
    Thanks!

    I see that a text about rails was added, thank you, who ever did that( you should credit yourself too! )! :D
     
  5. Djolovicl

    Djolovicl Retired eTeknix Janitor Forum Mod

    Joined:
    Mar 18, 2013
    Messages:
    2,206
    Likes Received:
    215
    Good read, thanks.
     
  6. Gurtej Singh

    Gurtej Singh Well-Known Member

    Joined:
    Dec 6, 2012
    Messages:
    503
    Likes Received:
    24
    Location:
    Ludhiana, Punjab, India
    Show PC Specs
    CPU:
    AMD Sempron 145 Processor
    Motherboard:
    Simmtronics NV 7050
    Memory (RAM):
    4 Gb
    Storage:
    500 Gb Samsung Seagate HDD
    Graphics Card(s):
    ATI Radeon 3000 Graphics Card
    Case:
    Intex Orion
    Monitor(s):
    Samsung Samtron 17''
    Operating System(s):
    Microsoft Windows 8 Pro
    wow nice info
    Thanks for sharing:)
     
  7. ana3mic

    ana3mic Active Member

    Joined:
    Jan 29, 2011
    Messages:
    421
    Likes Received:
    27
    Location:
    Bulgaria, EU
    Show PC Specs
    CPU:
    Intel i5-760
    Motherboard:
    ASUS P7P55D PRO
    Memory (RAM):
    Corsair Vengeance LP White
    Storage:
    Kingston V200 128GB + 2x1TB + 2TB HDDs
    Graphics Card(s):
    GIGABYTE GTX 670 OC
    Power Supply (PSU):
    Corsair HX850
    Case:
    Cooler Master 690 II Adv
    Monitor(s):
    Dell UltraSharp U2311H
    Operating System(s):
    Windows 7 x64
    Great How-to, I can attest that all the information is true and that's more or less the bare minimum one has to know about PSUs.
     
  8. grumpydaddy

    grumpydaddy Forum Mod

    Joined:
    Aug 19, 2011
    Messages:
    694
    Likes Received:
    49
    Location:
    Plymouth UK
    Show PC Specs
    CPU:
    3770K
    Motherboard:
    MVG
    Memory (RAM):
    G-Skill 2400 TridentX
    Storage:
    240G 840 Pro
    Graphics Card(s):
    hd7950
    Power Supply (PSU):
    seasonic x-650
    Case:
    Lian Li PC90B
    Monitor(s):
    Dell 24"
    Operating System(s):
    Win7 Ult
    Internet Connection:
    http://speedtest.net/result/2069640221.png
    Just a link for you to append.

    You can find information including efficiency/power graphs about most power supplies that have been 80Plus certified at:

    http://www.plugloadsolutions.com/80PlusPowerSupplies.aspx

    and...

    On the subject of how much power will your potential build use you can find a lot of information by looking at reviews.... especially those for graphics cards because, perhaps surprisingly, the figures quoted for these is usually a number for the whole rig.

    For Graphics cards alone the figures are fewer and further between but because these cards are often the most power hungry element of your build you can also use a rule of thumb.

    The slot specification for pci-e x16 when using a graphics card is 75 watts (3.3 V/3 A + 12 V/5.5 A), The Optional pci connectors add 75 W per 6-pin and 150 W per 8-pin power connector for up to 525 W total (75 W + 3×150 W). So just by looking at how many and what type of connection are needed for your graphics card you can know the maximum it was designed to use..... particularly useful if you want to add another for X-fire or SLI :)

    example: card with 2 6pin connections = 2*75 + 1*75 (MB) = 225w

    Lets take this a step further.

    We know that a single 6 pin connector is capable of 75 Watts so divided by 12v that gives us 6.25 amps. The 8 pin connector therefore is rated for 12.5 amps.

    Should you decide to buy a PSU with multiple rails that is NOT a high power design then you may need to be able to see the power available on each rail to ensure that your connectors spread the load evenly.

    With smaller psu's, multi-rail is a bit of a negative feature in my view because of this
     
  9. Sertineitor

    Sertineitor New Member

    Joined:
    Nov 23, 2014
    Messages:
    17
    Likes Received:
    0
    Location:
    Spain
    Show PC Specs
    CPU:
    AMD Phenom X3 8650 2,3GHz @2,5GHz
    Motherboard:
    AsRock Alive Xfire eSATA2
    Memory (RAM):
    2x2Gb Corsair & 2x2Gb Kingston @800MHz CL6
    Storage:
    WD Caviar Green 500Gb + Seagate video 500Gb
    Graphics Card(s):
    AMD ATi HD6870 1Gb GDDR5 + AMD ATi HD6850 1Gb GDDR5
    Power Supply (PSU):
    FSP Hyper 700W
    Case:
    Samurai
    Monitor(s):
    Acer 23" & LG L1717S
    Operating System(s):
    Windows 8 Pro 64bit
    Internet Connection:
    200Mbps/200Mbps
    Interesting guide.

    Regards
     
  10. Rich Summers

    Rich Summers New Member

    Joined:
    Nov 29, 2014
    Messages:
    19
    Likes Received:
    1
    Location:
    Maryland
    Show PC Specs
    CPU:
    QC-9400 2.6 -OC @3.8
    Motherboard:
    Asus Formula III
    Memory (RAM):
    5Gb- Mushkin DD2 800mhz
    Storage:
    Dual Velicaraptors 300Gb + 256Gb Raptor HDD & 1.5 TB WD Black HDD
    Graphics Card(s):
    Radeon R9 270X 4Gb DDR5 318Bit
    Power Supply (PSU):
    Antec 750 Watt Single Run w/ 6+6Pin
    Case:
    Xclio- ATX Full Tower
    Monitor(s):
    55" Panasonic Plasma Viera (First no Game-lag TV monitor produced) 1920 X1024
    Operating System(s):
    Win 8
    Internet Connection:
    Cab;e
    Great post, just what I was looking for th ru google search I found this site, very informative post on Power supplies, convinced me to use seasonic systems
     
  11. Rich Summers

    Rich Summers New Member

    Joined:
    Nov 29, 2014
    Messages:
    19
    Likes Received:
    1
    Location:
    Maryland
    Show PC Specs
    CPU:
    QC-9400 2.6 -OC @3.8
    Motherboard:
    Asus Formula III
    Memory (RAM):
    5Gb- Mushkin DD2 800mhz
    Storage:
    Dual Velicaraptors 300Gb + 256Gb Raptor HDD & 1.5 TB WD Black HDD
    Graphics Card(s):
    Radeon R9 270X 4Gb DDR5 318Bit
    Power Supply (PSU):
    Antec 750 Watt Single Run w/ 6+6Pin
    Case:
    Xclio- ATX Full Tower
    Monitor(s):
    55" Panasonic Plasma Viera (First no Game-lag TV monitor produced) 1920 X1024
    Operating System(s):
    Win 8
    Internet Connection:
    Cab;e
    If anyone has a link to a good multi color led fan controller post link please
     
  12. Stephenage1

    Stephenage1 New Member

    Joined:
    Nov 24, 2014
    Messages:
    12
    Likes Received:
    0
    would it be wise to get a power supply way above your needs, for say if the efficency was better at 70% load than the efficency of it at a higher load?
    also considering a new GPU so im guessing that little bit more couldnt hurt
     
  13. Badelhas

    Badelhas New Member

    Joined:
    Dec 28, 2016
    Messages:
    12
    Likes Received:
    0
    Very nice info, thanks!

    Cheers
     
  14. Ashley Chetty

    Ashley Chetty New Member

    Joined:
    Jan 15, 2017
    Messages:
    11
    Likes Received:
    0
    This is actually a really informative post for new pc builders on power supplies. Grear man:D
     
  15. Ashley Chetty

    Ashley Chetty New Member

    Joined:
    Jan 15, 2017
    Messages:
    11
    Likes Received:
    0
    This is actually a really informative post for new pc builders on power supplies. Great man:D
     
  16. sneijder

    sneijder New Member

    Joined:
    Sep 23, 2018
    Messages:
    3
    Likes Received:
    0
    Thank you for this topic, which I can only approve. A nice job!
    It saved me a lot of hours of research.


    ----------------------------------------------------------------------------------------------------------------------------------------
    Appvalley AC Market Tweakbox
     
    Last edited: Oct 4, 2018

Share This Page

Users Viewing Thread (Users: 0, Guests: 0)