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    Power Supply

    Section 1.0 - Power supply selection.

    Courtesy: AMD Builders Guide for Desktop/Tower Systems Article # 26003A — May 2002.

    For reliable operation, the output of the power supply must be greater than the maximum total combined wattage usage for the system configuration.

    In a standard single-user desktop/tower system, it should be apparent that the maximum wattage usage will be less than the combined total of all the components in the system.

    The maximum wattage is less because it is almost impossible to concurrently use the maximum power of all the components. Therefore, a power usage factor should be used.

    AMD suggests calculating the power supply minimum output capacity as the power required by the processor plus 80 percent of the total wattage for all the other components in a desktop/tower systems.

    This 80 percent value is not a hard and fast value. The system builder's in-house testing may change the power-usage factor.

    In addition to the overall wattage requirements, the builder must verify that the maximum voltage for the +5 V and +3.3 V power requirements for the system are less than the wattage limitation on the power supply for the +5 V and +3.3 V outputs.
    What should be on your mind when making a Power supply purchase.

    Whats the true capacity of your power supply? What I mean by that is not whats written on the side like "400W" I mean what are the amperage (A) specs for each voltage on the side of the power supply for:
    3.3V = ?A
    +5V =?A
    +12V =?A
    +5VSB =?A

    Will I be able to use this in a future upgrade?

    Is the Manufacturer known to be a quality power supplier manufacturer?

    Is there enough capacity on the 12V line for now and for the future? The 12V line is now being used by even more power hungry devices, as opposed to the general myth that only 3.3V & 5.0V are all that matter.


    Section 1.1 - UPS Selection.

    Instead of writing a long winded article about this I have found some links for you to browse:

    Courtesy: M+H Power Systems Pty. Ltd
    http://www.mhpower.com.au/nikobe/html/sizingguide.html

    Courtesy: UPSCI.com
    http://www.upsci.com/UPS-selection.htm

    Courtesy www.nooutage.com
    http://www.nooutage.com/UPSGuide.htm

    Again keep these questions in mind:

    Will I be able to use this in a future upgrade?

    Is the Manufacturer known to be a quality UPS manufacturer?

    When in doubt look for reviews, google is your friend.
    Ya'll think us folk from the country's real funny-like, dontcha?

    The opinions expressed above do not represent those of BADCAPS.NET or any of their affiliates.

    #2
    Re: Power Supply

    May or may not be a good place for this but it's interesting,
    http://www.smpstech.com/mtblog/elect...r_failure.html
    Jim

    Comment


      #3
      Re: Power Supply

      No problem, there are a lot more knowledgeable people out there...

      MD
      Ya'll think us folk from the country's real funny-like, dontcha?

      The opinions expressed above do not represent those of BADCAPS.NET or any of their affiliates.

      Comment


        #4
        Re: Power Supply

        Originally posted by arneson
        May or may not be a good place for this but it's interesting,
        http://www.smpstech.com/mtblog/elect...r_failure.html
        "One of the most powerful methods for troubleshooting electronics is unplugging power."

        http://www.smpstech.com/mtblog/

        days are so short when you actually do something..

        Comment


          #5
          Re: Power Supply

          about active pfc and why it's not about saving your electicity bill..

          PF - http://www.pcper.com/article.php?aid...=expert&pid=11
          PFC decoded - http://www.dansdata.com/gz028.htm
          Work, Power & Apparent Power - http://www.pcguide.com/ref/power/ext/basics.htm
          Testing Power Factor (PF) - http://www.systemcooling.com/tt_twv480-05.html
          APFC Myth - http://www.silentpcreview.com/article28-page5.html

          please, if someone here can explain it in his own understanding..
          days are so short when you actually do something..

          Comment


            #6
            Re: Power Supply

            I have read some of the links. The dansdata link is probably the simplest to understand and most accurate. One article has an error quoting passive PFC adds a capacitor. All PS have capacitor input and normally an inductor is used to add correction.

            Active PFC usually comprises a pre convertor to over come the capacitor input effect and load changes. An example is covered in a TI abstract at: http://focus.ti.com/analog/docs/tech...ctName=slua369

            Hope this helps.
            Gigabyte EP45-DS3L Ultra Reliable (Power saver)
            Intel E8400 (3000Mhz) Bios temps. 4096Mb 800Mhz DDR2 Corsair XMS2 4-4-4-12
            160Gb WD SATAII Server grade
            Nvidia 8500GT 256Mb
            160Gb WD eSATAII Server grade for backup.
            Samsung 18x DVD writer
            Pioneer 16x DVD writer + 6x Dual layer
            33 way card reader
            Windows XP Pro SP3
            Thermaltake Matrix case with 430W Silent Power
            17" Benq FP737s LCD monitor
            HP Officejet Pro K5300 with refillable tanks

            Comment


              #7
              Re: Power Supply

              yanz, I found this PFC article better stated without being over technical, for me anyway.
              http://www.rojakpot.com/showarticle....rtno=81&pgno=0
              (look at Adrian's BIOS Guide)

              Dan'sDATA states, that in this case efficiency takes a 10% hit but SPCR states a 3~5% loss. I prefer having APFC PSUs.

              Comment


                #8
                Re: Power Supply

                Well dealing now more and more with old and newer systems i `ve noticed that psu makers changed their produkt dramatikally.

                In the beginning of the amd Athlon the important nummber of an PSu was the 3,3&5v combined power. This is still true for all systems which power the cpu and other stuff from the 5v and 3,3v rails, e.g mainboard lacking the 12v 4 pin conector ("p4" connector).
                Famouse for beeing an current hungry beast are the k7s5a and simmilar desings and most asrock mainboards too (k7s8x**, only 2 phases and only 5v will need mutch power).There are board from all other vendors too.

                Today most systems will power the cpu from the 12v line.
                Now for an psu maker it is easy to increase the 12v power, due to the relative low amps which are needded. To save some bucks most new psu´s can only deliver a ver very small ammount of power on the 5&3,3v lines (e.g Amacrox , Fortron 150w combined power for an 500w psu or 130w combined power for a 350w psu).
                It is clear, that any of that 500 or 600w rigs can`t stand an old soket A system, which don`t have an 4pin 12v connector.
                And may be this is one of the reasons, why some DFI mainboards eat psu`s. They drain to mutch from the 3,3 and 5v and therefore kill the new psu`s.

                At the moment i don´t know of any psu which can handle both, the high combined power and the high 12v power. probalby only the older higher wattage units can handle both, but they are rare to find.
                May be, some ofnthe psu makers starts thinking and will make some decent units withoutn skimping something down.

                Comment


                  #9
                  Re: Power Supply

                  Originally posted by gonzo0815
                  At the moment i don´t know of any psu which can handle both, the high combined power and the high 12v power. probalby only the older higher wattage units can handle both, but they are rare to find.
                  These PSUs are capable.
                  http://www.2themax.com/power_mp_ep_x.html

                  They can supply 220w or more on 3.3v & 5v combined
                  while they also feature dual rail 12v.
                  ******************************************

                  Comment


                    #10
                    Re: Power Supply

                    Another link reguarding Active PFC. Just happened on this one yesterday.


                    Comment


                      #11
                      Re: Power Supply

                      Originally posted by Galvanized
                      yanz, I found this PFC article better stated without being over technical, for me anyway.
                      http://www.rojakpot.com/showarticle....rtno=81&pgno=0
                      (look at Adrian's BIOS Guide)

                      Dan'sDATA states, that in this case efficiency takes a 10% hit but SPCR states a 3~5% loss. I prefer having APFC PSUs.
                      that's a good link.

                      10%, i dont agree with that. in reality, it should be 5-10W (not in %). cmiiw.
                      days are so short when you actually do something..

                      Comment


                        #12
                        Re: Power Supply

                        It is absolutely not correckt to say that A-PFC PSu`s will be less efizient than others. In fact, all availible A-PFC PSU`S i`ve seen are in most cases far more eficient then those w/o.

                        It is clear, that the absolut best PSU without A-PFC will be more efficient compared with the absolut best of an A PFC unit. But those highly efficient P-PFC PSU are at the moment not availiable. Whereas many a-PFC units are availiable with efficiency numbers up to 85 % or even more.
                        So as long, as no non- or P-PFC psu will reach those numbers, this will be pure theoretical numbers.

                        Comment


                          #13
                          Re: Power Supply

                          Many people misunderstand about efficient & PFC.
                          Even some PSU reviews stated PFC lead to better efficient.
                          Those reviews just like a saleman fooling his customers.

                          In fact, most A-PFC PSUs are built with better components as compared with
                          their non/P-PFC counterparts. Better components sometimes lead to higher efficiency.
                          In this way, people will attribute higher efficiency to A-PFC.
                          ******************************************

                          Comment


                            #14
                            Re: Power Supply

                            I think reviewers are just being imprecise. Whether active or passive PFC, compnents are added that dissipate power, so the efficiency of the P/S is reduced compared to non-PFC. However, due to the narrow conduction angle of non-PFC and the consequent potential for very high Neutral currents and IR drops in phase wires, PFC can improve efficiency in the power grid.
                            PeteS in CA

                            Power Supplies should be boring: No loud noises, no bright flashes, and no bad smells.
                            ****************************
                            To kill personal responsibility, initiative or success, punish it by taxing it. To encourage irresponsibility, improvidence, dependence and failure, reward it by subsidizing it.
                            ****************************

                            Comment


                              #15
                              Re: Power Supply

                              This post has slightly diverged I think off its original topic, anyway since its here

                              Think PeteS has more or less hit the nail on the head here as to why the big swing to pfc correction with SMPSU's

                              My understanding was the power companies had to worry about reactive/ apparent power losses.


                              How they do this I don't know but at some point I guess they have to correct or compensate for this, which probably costs $$$

                              Since new laws and specs have been brought in, I guess this is now being forced on to the MFR to produce more Grid friendly devices in respect to power factor correction.
                              (this may have been brought about by the power moguls putting pressure on the government...I don't know)

                              There is now a lot of garbage equipment that hangs off the mains system and switchers are just about everywhere these days, Even Wall warts are switchers so I suppose sooner or later MFR's were going to be forced to make better equipment

                              This I suppose has resulted in MFR's complying (cause they want to sell in these countries) but of course has added extra costs so their only way out is to use "Hype" to customers as to "why" they should buy their supplies over others...really half truths at best as far as the customer is concerned.

                              PeteS also raising an interesting point.(if not directly)

                              How much real power is expended to correct for reactive power losses ?.

                              Me, well at the end of the day if it results in an over all more efficient cleaner use of the grid which hopefully results in less fossil fuels being burn...then why not I don't mind paying a bit extra.

                              Don't know weather this would be the case but hope it would be

                              If I get a better designed, more efficient and better quality power supply because of it then all the better.

                              Just my thoughts on it

                              Didn't read it but looked interesting here
                              Last edited by starfury1; 11-30-2006, 06:43 AM.
                              You step into the Road, and if you don't keep your feet, there is no knowing where you may be swept off to." Bilbo Baggins ...

                              Comment


                                #16
                                Re: Power Supply

                                Well, the compensation issue is realy a $$ thing. In Germany any hughe profesionall elektricity consumer is urged to pay for it`s power factor, unless they compensate them by there own. This is a valid part in the contract. Thus any professionall equipment like elektronic fluorescent bulb balasts, motors etc. have A -Pfc or compensation caps for a long time here. And most companies invest in their own compnesation banks, if they have huge motors or other reactive devices. The other benefit is as mentioned before, the circuit brakers and the whol grid can be sized to the real values and the issues abouth strange potential differences betwen different facilities is reduced. Any way, the IT equipment was no the thing, people are aware of the problem. Thus it was largely ignored. From this point of view, i think it was a great idear from the EU, to make the compensation for devices abouth a significant power level mandatory. In the end it is a win for all stakeholders, environment, consumer and industry, if the cost for compensation are charged to the one who caused it.

                                Comment

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