Recommend Me a SMPS?

Discussion in 'hardware' started by subhrobhandari, Jun 8, 2010.

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  1. subhrobhandari

    subhrobhandari Registered Member

    Nov 6, 2009
    Well, it started around one month ago. My computer sometimes wont start, just before starting on the monitor or after it will get shut. After pressing power button 3-4 times it will eventually start and would not show any kind of problem after that. Sometimes it will allow me to see the INTEL logo for awhile and then shut. I just did not have enough time to check the hardwares as I were busy with some family matters.

    Today I replaced my old SMPS with a new one and it worked flawlessly, rebooted numerous times without any problem. The question is how much rating (the current one is 600W) should I use for my SMPS and is there any way to prevent them from burning out? I changed another one year ago, in the summer.

    Here's my Specification:

    M/B: Intel® Desktop Board D101GGC
    Processor: Pentium D 2.66 GHz
    Monitor: LG 700B (17" CRT)
    Speakers: 800W Intex Sub-woofer (I hardly use them, pretty happy with my iBall i342MV Headphone)

    There are no other external hardwares, Video Card and Graphics is embedded, uses 64 MB from my 768 MB RAM. All hardwares are cleaned and the Thermal Adhesive is fine too. Power supply and the cords are checked. CPU temperature is around 60 deg. Celsius and the fan's RPM is around 1800-2000 normally. While I am not doing any intensive tasks the CPU is less then 2-3%.
  2. Bill_Bright

    Bill_Bright Registered Member

    Jun 29, 2007
    Nebraska, USA
    Please understand the accepted term is power supply unit, or PSU. All computer PSUs use switching mode technologies these days but if you say SMPS, most folks will scratch their heads and say, "huh?"

    If you have to keep replacing PSUs, you are either buying cheap, off-brand PSUs, you have some lousy power, or just bad luck.

    I recommend all computer owners, home owners, and apartment dwellers to buy a AC Outlet/Ground Fault Indicator Tester and test all their wall outlets. There is a version for all type outlets and voltages - depending on what is used in your country.

    Below is my canned text on sizing and selecting a new PSU. Note the comment about using a good UPS with AVR. Sadly, many people think of a UPS for battery backup only but that is actually its minor role. Regulating and cleaning up dirty power is the primary role of a good UPS w/AVR - thus taking the burden, and abuse away from the power supply and motherboard regulator circuits.

    Use the eXtreme PSU Calculator Lite to determine your minimum power supply unit (PSU) requirements. Plug in all the hardware you think you might have in 2 or 3 years (extra drives, bigger or 2nd video card, more RAM, etc.). Be sure to read and heed the notes at the bottom of the page. I recommend setting Capacitor Aging to 30%, and if you participate in distributive computing projects (e.g. BOINC or Folding@Home) or extreme 3D animated gaming, I recommend setting both TDP and system load to 100%. These steps ensure the supply has adequate head room for stress free (and perhaps quieter) operation, and future hardware demands. Research your video card and pay particular attention to the power supply requirements for your card listed on your video card maker's website. If not listed, check a comparable card (same graphics engine and RAM) from a different maker. The key specifications, in order of importance are:
    1. Current (amperage or amps) on the +12V rail,
    2. Efficiency,
    3. Total wattage.
    Don’t try to save a few dollars by getting a cheap supply! Digital electronics, including CPUs, RAM, and today's advanced graphics cards, need clean, stable power. A good, well chosen supply will provide years of service and upgrade wiggle room. Look for power supply brands listed under the "Good" column of PC Mechanic's PSU Reference List. Note that some case retailers “toss in” a generic or inadequate PSU just to make the case sale. Be prepared to “toss out” that supply for a good one with sufficient power.

    Most PSUs have an efficiency rating of around 70%. This means for every 100 watts of power a PSU draws from the wall, only 70 watts is delivered to the motherboard, with the rest wasted in the form of heat. The best supplies are 85 to 90% efficient, and as expected, cost more. I strongly recommend you pick a quality supply with an efficiency rating equal to or greater than 80%. Look for 80 Plus - EnergyStar Compliant labels.

    Too big of a PSU hurts nothing but your budget. Your computer will draw from the PSU only what it needs, not what the PSU is capable of delivering. If a computer needs 300 watts it will draw 300 watts regardless if the PSU is a 350W, 650W, or 1000W PSU. In turn, the PSU, regardless its size will draw from the wall only what it needs to support the computer. In this example, it will draw 300 watts, plus another 45 – 90 watts, depending on the PSU’s inefficiency.

    As noted, the eXtreme Calculator determines the minimum requirements. If the calculator (with the changes I suggested) recommends a 400 watt minimum, a quality 400W supply will serve you just fine. But a quality 550W – 600W supply will have, among other things, larger heat sinks to dissipate potentially more heat. It might have a larger fan too. The 400W supply will run most of the time closer to capacity, while the larger supply will be loafing along, rarely breaking a sweat. To help the smaller heat sinks get rid of the wasted 80 watts (20% of 400) of heat, the fan in the 400W supply may need to run full speed, while the fan in the larger supply, with bigger sinks just loafs along too – but in near silence.

    Don't forget to budget for a good UPS with AVR (automatic voltage regulation). Surge and spike protectors are inadequate.
    Note that 60°C is the threshold where I start to get nervous. 60°C is not "high", but it is pretty warm. I don't think that is your problem with PSUs, but if you start to have stability issues, heat may be the cause. Make sure you keep the interior of your case clean of heat trapping dust, and you might consider adding another case fan or two to ensure adequate front to back air flow through the case.

    Also note you should not be using thermal "adhesive" on CPUs. "Adhesive", as the name implies, is a glue. And you don't glue heat sinks to CPUs, you clamp them together. Thermal "adhesive" is used on some graphics cards and chipsets where there is no mechanism to clamp the heatsink to the board or card. For CPUs, you should use a very thin layer of non-adhesive thermal compound. I also have a canned text for applying a proper layer of TIM (thermal interface material) I can post, if you like.
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