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Do a 650W PSU use 650W all the time?
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Do a 650W PSU use 650W all the time?

I have a couple of servers at home, one with a 550W PSU and one with a 650W PSU.
Do they use all the W at all time, or do it depend on the load?
Both my CPUs has a TDP @ 80W - no GPU, but some hard drives. And some fans.
How much do they use do you think, if the W used is based on what hardware that are in use?

Comments

  • Depends on the load and efficienty

    Thanked by 2myhken WSS
  • If your electro-math sucks but you really want to know

    Thanked by 2myhken netomx
  • The PSU's wattage is what it can supply, not what it constantly uses. Lets spit ball some figures, 80w cpu, 2 fans a 5w each and 2hdd at 10w each.
    110w as a base load, throw in 80% efficiency.
    ~130w under full load.

    If your power usage is something that interests you in monitoring more consistently I'd recommend getting a device to do as such, it'll be far more accurate for you to use.

    Thanked by 1myhken
  • Umcookies said: throw in 80% efficiency

    Any reasonable ATX power supply will do more than 80% efficiency on any % draw above 20%.

    Umcookies said: 110w as a base load

    No server will run at 100% CPU load and certainly none will run at more than 90% right from start, so more like half of that if not less.

    Thanked by 1myhken
  • What is the CPU? How many hard drive / what kind?

    A sandy bridge i5 with 1SSD + 1 2.5 HDD can use around 20/30 watts idling or doing low load stuff (with a rather efficient PSU).

    Depending the exact CPU type, how efficient is your PSU, how many HDD you have and how much each of those consume, you're probably using around 50 watts idling / doing low load stuff or something close.

    Thanked by 1myhken
  • My DL360 uses around 230 watts with 2x x5670 and 8x 10k sas drives.

    Thanked by 1myhken
  • @myhken No.

    Baseline of fixed minimum power when on and an efficiency curve above that - variable but not unpredictable load. PSUs tend to fail fast when loaded to the max for a long period of time.

    Thanked by 1myhken
  • imho those 50W for server with i5 while idling is probably very optimistic assesment. My own server is taking ~40W idle (measured) but I achieved this after a lot of tweaking (xeon-d, low-power fans/ssd/ddr, 80+/gold psu, no graphics, etc)...

    Thanked by 1myhken
  • Thanks for all replies. So SERVER1 has a older i5 4690K CPU, and have 8x normal hard drives, and 3 x SSD drives internal. It also have 3 x external USB docking stations, but they all uses their own power supply.
    SERVER2 has a XEON E3-1245v5 CPU, 2 x normal HDDs and 4 x SSD drives. I can see that the XEON CPU has really good power management, and is almost not in use. It uses between 3 and 5 W at normal use. The 4690K is using between 10-20W on any given time

  • TamerciagaTamerciaga Member, Host Rep
    edited January 2017

    TDP of your CPU is related to heat, not power:
    https://en.wikipedia.org/wiki/Thermal_design_power

    650W PSU can provide up to 650 watt of power, it will not draw that amount by default, only if it's "asked".

    Thanked by 1myhken
  • Use this tool to get an idea - http://outervision.com/power-supply-calculator

    If your servers have IPMI read this - https://serverfault.com/q/389224

    Thanked by 1myhken
  • Is this a troll thread?

    Thanked by 1Frecyboy
  • WSSWSS Member

    I use cap droppers everywhere. Every so often you get a crash and a small stain of dark goo.

  • No it doesn't use 650W at all time.

    Thanked by 1myhken
  • It doesnt use 650W at all time. Components have power saving features, not only to save power but also to generate less heat.

    A 650W PSU, wont be able to provide the 650W due to efficiency, it depends on what power supply you have but usually is about 80%.

    Efficiency has a "curve", a power supply is mostly efficient when 50% of the power is being used.

    Thanked by 1myhken
  • @WSS said:
    I use cap droppers everywhere. Every so often you get a crash and a small stain of dark goo.

    Ooooh. Make me a cap drop phone charger and I'll pay you $100000, even though the likelihood of me surviving after getting electrocuted is quite low ;)

  • dragon2611dragon2611 Member
    edited January 2017

    What Voltage? 110 or ~230

  • @dragon2611 said:
    What Voltage? 110 or ~230

    ~230

    @tr1cky said:
    Is this a troll thread?

    No, I'm not know for trolling. I really want to know about this and how much power my servers is using.

    But I think I have got a good idea now.

    Thanked by 1netomx
  • WilliamWilliam Member
    edited January 2017

    Jarry said: xeon-d

    A Xeon-D is not an E3 which also exists as L variant. Entirely different beats, both in efficiency design and usage.

    We have a bunch of i7-3770 here that comfortably use on full load about 15% over CPU TDP (incl. fans etc.) - less than 100W for the entire system.

    Qarizma said: TDP of your CPU is related to heat, not power

    Oh boy, how you think that heat is generated, by magic? The TDP is just the non-used capacity (yea, yea, for simplification); the actual usage is the same or higher by thermodynamic laws.

  • JunklessJunkless Member
    edited January 2017

    @vovler said:

    A 650W PSU, wont be able to provide the 650W due to efficiency, it depends on what power supply you have but usually is about 80%.

    If I am not wrong, that is NOT how it works. A 650W PSU will always be able to provide 650W, irrespective of the Efficiency rating. Just that, a lower rated PSU (i.e. non 80+) will draw more power from the wall socket to provide the same 650W in comparison to an 80+ (or better) rated PSU.

    A 650W PSU with 65% efficiency will pull 1000W from the wall socket to provide those 650 Watts. While a 650W PSU with 85% efficiency will pull only 765W (approx) from the wall to provide the same 650 Watts of power.

    Thanked by 4Yura myhken vimalware WSS
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