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Thread: M3 is enough?

  1. #1
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    M3 is enough?

    I just had my M2 crap out last Friday and need to order a new PSU. Here's my list

    EPIA-EN 15000G -17watts?
    1GB DDR2 4200 RAM - 4watts?
    1 2.5" SATA HDD - 2.5W 5V/7.2W 12V
    Lilliput 7" VGA Touchscreen 629GL-70NP converted to the PSU power - 9 watts
    Panasonic UJ-85J-B Slim Slot load DVD±R/±RW/+RDL/RAM Multi Drive - 10 watts
    Mini-Key USB Keyboard DGPN-570 - 2watts?
    USB bluetooth dongle - 2watts?
    USB GPS receiver - 2watts?
    D-link USB wifi adapter - 2watts?
    PCMCIA USB adapter - 2watts?
    and sometimes a USB thumbdrive - 2watts?
    USB 5.1 surround sound card (ZM-RSSC) - 2.5watts?
    HQCT USB -



    The M3 should technically be enough juice for the system and since its all behind the screen (in-dash) the smaller footprint, the better. Did I calculate this correctly? Any bad reviews on the M3?

  2. #2
    Fusion Brain Creator 2k1Toaster's Avatar
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    You cannot calculate these decisions based on total wattage. You have to calculate it based on total current draw for each rail.
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  3. #3
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    Quote Originally Posted by 2k1Toaster View Post
    You cannot calculate these decisions based on total wattage. You have to calculate it based on total current draw for each rail.
    OK how would I go about doing that?

    Looks like 12V is 6A = 72W
    5V is 6A = 30W
    and basically everything except part of the SATA and the DVD burner will be on the 5V?
    If so, then I got
    about 53W on the 12V and about 13W on the 5V

  4. #4
    Maximum Bitrate FusionFanatic's Avatar
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    PSU wattage is used to state a PSU's output power in a single number (total watts). this makes it easier for marketing the PSU, but this number alone is useless in determining if a PSU is powerful enough for your specific system. each power rail has it's own maximum output and power cannot be shifted from rail to rail.

    you don't need to calculate the wattage for each rail, in fact you don't need to calculate wattage at all. you need to know how many amps each power rail can provide, and how much current your computer/system needs from each rail.

    at ~12v input; the M3-ATX can provide a max 3.3v@6A, 5v@6A, and 12v@6A. since you calculated your system needs at around 6A on the 5v and 12v rails then the M3-ATX will be completely taxed (if it works at all).

    I think it's safe to say that M3-ATX is not powerful enough for your system

  5. #5
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    Quote Originally Posted by FusionFanatic View Post
    PSU wattage is used to state a PSU's output power in a single number (total watts). this makes it easier for marketing the PSU, but this number alone is useless in determining if a PSU is powerful enough for your specific system. each power rail has it's own maximum output and power cannot be shifted from rail to rail.

    you don't need to calculate the wattage for each rail, in fact you don't need to calculate wattage at all. you need to know how many amps each power rail can provide, and how much current your computer/system needs from each rail.

    at ~12v input; the M3-ATX can provide a max 3.3v@6A, 5v@6A, and 12v@6A. since you calculated your system needs at around 6A on the 5v and 12v rails then the M3-ATX will be completely taxed (if it works at all).

    I think it's safe to say that M3-ATX is not powerful enough for your system
    So then I'm stuck with the M2. Which M2 though?
    M2-ATX 6-24V DC/DC (160 Watts)
    M2-ATX-HV 6-32V DC/DC (140 Watt)
    or what about the M4?
    I think I might just go once again with the original M2 and hope it doesn't crap out again after a year

  6. #6
    Maximum Bitrate FusionFanatic's Avatar
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    you're not stuck with anything. you're just choosing PSUs that are not powerful enough for your setup. remember, when searching for a PSU, the total wattage does NOT matter. look only at the power rail amperage ratings. check out the MP3car store's PSU section. there are several DC-DC PSU models that can handle your system. when you read the product descriptions, click on the "technical specs" button (under the product picture) to see the individual rail output ratings.

    the M2-ATX and M2-ATX-HV have the same output power (140w max, 160w peak). the only significant difference is the '-HV' model has a wider input voltage range. it's irrelevant in your case anyways because it still can't handle your system with any headroom. the M2-ATX / M2-ATX-HV can provide 3.3v@6A, 5v@6A, and 12v@7A. it's only slightly more powerful than the M3-ATX. your M2 probably died because you were pulling too much juice from it. if you buy another one it will likely die just as quickly.

    the M4-ATX is significantly more powerful. at ~12v input it can provide 3.3v@15A, 5v@15A, and 12v@12A. that should be able to easily handle your system, and gives you headroom for future expansion/upgrades.


  7. #7
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    Quote Originally Posted by FusionFanatic View Post
    you're not stuck with anything. you're just choosing PSUs that are not powerful enough for your setup. remember, when searching for a PSU, the total wattage does NOT matter. look only at the power rail amperage ratings. check out the MP3car store's PSU section. there are several DC-DC PSU models that can handle your system. when you read the product descriptions, click on the "technical specs" button (under the product picture) to see the individual rail output ratings.

    the M2-ATX and M2-ATX-HV have the same output power (140w max, 160w peak). the only significant difference is the '-HV' model has a wider input voltage range. it's irrelevant in your case anyways because it still can't handle your system with any headroom. the M2-ATX / M2-ATX-HV can provide 3.3v@6A, 5v@6A, and 12v@7A. it's only slightly more powerful than the M3-ATX. your M2 probably died because you were pulling too much juice from it. if you buy another one it will likely die just as quickly.

    the M4-ATX is significantly more powerful. at ~12v input it can provide 3.3v@15A, 5v@15A, and 12v@12A. that should be able to easily handle your system, and gives you headroom for future expansion/upgrades.

    Thanks
    I'll order the M4, and reading the manual online looks like very little modification is needed to get it to work.

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