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  1. #1
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    May 2004

    Is this big enough?

    I have an ecs (elite group) k7s5a pro motherboard. I have been leed to believe that this is a very power hungry motherboard that requires more power than your average mother board. I'm running the following
    amd athelon xp2400
    2 256 mb ddr 2700
    agp radeon 7000 64mb
    soundblaster 512
    pinnacle pctvpro card
    us robotics performance pro modem card
    two maxtor hard drives
    network card
    liteon 851s dvd burner
    maddog dvd rom
    I have been running a deer (yea, I know, it's a cheapo) 300 watt power supply with 3.3v-20A, 5v-30A, 12v-10A
    The system tends to crash but not too often. I think it hapens the most when I start copying a dvd. Most of the time it copys ok but it sometimes crashes (and crashes at other times). I think the power supply is the problem. I emailed ecs and they said 300-400 watts with 28A on the 3.3v. I emailed them again trying to get more specific info and they just said use a 400w or 450w power supply to be safe.
    I intend to add a siig raid card and two hitachi hard drives. I already spent all my spare money on the card and drive just to discover that the case and power supply were not really up to the task. I got an antec plusview 1000amg which has lots of room, bought round cables and extra fans (the old case only had 1)so I'm pretty broke. I still need a beter power supply.
    I intend to run two power supplys. I made a small circuit board with a 20pin motherboard power conector, a 4 pin conector, a relay, a resistor with a small heatsink and a conector for an led so I know the second power supply is powered up. This should allow the first power supply to turn on the second power supply and provide load on the 3.3v (5v and 12v will get load from drives). I want to get a enermax eg375 350 watt power supply that rates at 3.3v-32A, 5v-32A, 12v-26A. It has 185 watts for the 3.3v and 5v so if it is running 32A on the 3.3v, it should have about 16A left on the 5v (max). Acording to the watage it should only have about 14A avalable on the 12v so I don't know how they rate it at 26A. Perhaps it can share power between all three voltages so it can do 26A if not all the 3.3v and 5v are used.
    All the enermax has to power is the motherboard and attached components plus a drive or two. I can run most of the drives (particularlly the power hungry dvd drives) and fans off the deer power supply. I would like it to be a little bit overkill just to guarentee enough power to the motherboard and attached components but money is very limited. Does anybody think that the enermax is too small with all that stuff on the motherboard or will it be plenty big enough. It was running (though prone to crash now and then) with 3.3v-20A, so 32A should be plenty, right?
    Fyi I chose enermax because they seem to have higher amperages with 3.3v (with a little cost to the 5v) than many other power supplies and they seem to be decent quality (compared to the cheapo ones anyway). If I have to get biger than 350watt I will but I cannot even afford the 350watt right now.
    Any opinions would be greatlly appreciated!!

  2. #2
    Senior Warranty Validity Sealed Stick Remover Oklahoma Wolf's Avatar
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    Welcome to the forums

    Replace the Deer - more than just cheap, they're dangerous for other components too. Very poor build quality - the worst I've ever seen to date.

    A friend of mine has two of these boards - one's running from a Channel Well (Antec OEM) 300w unit, and the other a Channel Well 375w. Neither have any power related issues. I would suggest a Fortron 350w or better, or Antec 380w or better for running the whole system. The Enermax mentioned should also run things ok by itself, but wouldn't be my first choice.
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  3. #3
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    May 2004
    Thanks. I have decided to completly scrap the deer. I was looking at a coolergiant(enermax) eg485p 480watt power supply. It has ample 3.3v and 5v (280 watts combined) but I am a little concerned about the 12v as they split the power to two rails. I'm not sure it will be enough if I get a couple more drives to upgrade my raid down the road. It kind of depends on how the power sharing works. I've decided to go with a single larger power supply anyway.
    Fyi, am I understanding right? The power supply can share power between all three voltages up to the rated amperage for a particular voltage, right?
    Last edited by ripit; 05-18-04 at 11:17 PM.

  4. #4
    Senior Warranty Validity Sealed Stick Remover Oklahoma Wolf's Avatar
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    The 480w Coolergiant is more than enough for that system, even with more drives.

    How well a PSU can meet its ratings depends on a few things, not the least of which is overall build quality and design... most can only meet the full rating on one rail if others aren't stressed fully themselves. All rails are limited in total output by the amount of power the primary side of the PSU can regulate (ie, the section of the PSU that processes the incoming 120v AC power from the wall).

    To make things complicated, many PSUs are rated at a lower temperature than the PSU normally operates at. Enermax for example rates all their units for full power at 25 degrees, decreasing to 80% at 40 degrees. Not sure what the normal operating temps on the Coolergiants are, but it's unlikely you'd need all 480w anyhow.

    Hope that helps some - I'm half asleep and not sure I'm making much sense
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  5. #5
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    Thanks for the help and sure it makes sense. I generally understand how they work. The part that I am not 100% certain on is if it can share across all three channels. That confuses me because they always give a wattage rating for the 3.3 volt and the 5v combined. the cooler giant has 280 watts max for the 3.3v and 5v. I understand how that part of it works. If you are using the full rated 34 amps at 3.3v, that uses 112 watts, leaving 168 watts that the 5v can use, which is 33.6 amps (a healthy portion of the rated 40 amp capacity, one thing I like about this power supply). As it is a 480 watt power supply, if the 3.3v and 5v are fully loaded, that leaves 16.6 amps for the 12v. the 12 volt is split into two rails on this power supply, the first rated at 16 amps, the second rated at 15 amps. I am assuming but do not know absolutlly for sure that the two 12v rails can share so that you could be using 4 amps on the first and 12 amps on the second out of that 16 amps. Further I do not know for sure if the 3.3v/5v can share some of that 280w with the 12v rails, so that they can use more than 200 watts. If the 3.3v and 5v are only using 200 watts together for instance, does the 12v have 280 watts that it can use?
    By the way I know that these are maximums and you are only suposed to run at about 70 percent capacity or less for good performance (or so I have heard), and I know that the power supply may not be able to put out those maximums if it is hot. I am more wondering how the power sharing works. My concern is that my current drives take about 8 amps. if I add two more drives to my raid down the road (another 1.5 amps for two hitachi's) and you add case fans and lights (I know they don't pull much but it adds up, especially with 6 lit fans and a psu fan that pulls .66 amps). I could easilly be pulling 70% (or even a little more) of that 15 amps that it is rated at so I would need the full power of that rail. That is why I wonder how the sharing works.Granted that is going off the drives specs which I assume is the maximum they will pull. Since it is unliklly that all the drives will be going full boar at the same time, perhaps it will use a bit less.
    Fyi I already bought and installed the coolergiant so I am just looking for a little piece of mind.

  6. #6
    Senior Warranty Validity Sealed Stick Remover Oklahoma Wolf's Avatar
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    Originally posted by ripit
    if the 3.3v and 5v are fully loaded, that leaves 16.6 amps for the 12v.
    This is what I really dislike about Enermax - their labeling practices really need some work. My current understanding is that Enermax has these designed so that nice 12v rating on the label can only be attained if the 3.3v and 5v rails aren't running at full power, and the PSU is running at 25 degrees. That said, I am certain the 480w will handle all the drives fine - except for the drives, I don't think you have any other significant load on the 12v. Even with the board sucking most of the 3.3v/5v output, there will still be plenty for the drives... I'd estimate a good 16-20a.

    Also, I'm not sure I believe just yet there really are two seperate 12v rails - I think Enermax saved a few bucks and took both from one source (could be wrong though - I need to examine one in person to be sure).

    In case you're still worried, since that ECS board is 5v CPU based and mine is also 5v based, here's my own experiences with the 420w CWT in my main rig: it's run 5 hard drives and 3 opticals at once under a heavy overclock. I can't put a dent in the rails on a multimeter - it laughs at me every time. My 12v is rated at 18a, and gets the least stress no matter how many drives I plug in. You'll be fine, I'm 100% sure
    Last edited by Oklahoma Wolf; 05-19-04 at 10:23 PM.
    Asus P8Z68 Pro-V Gen3
    2500K w/ Thermalright Ultra-120 Extreme
    16GB G.Skill Ripjaws
    Inwin GRone, Corsair AX860i
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    250GB Samsung 840 Evo, 640GB WD Black, 2TB Samsung F4, 3TB Seagate 7200.14
    Lite-On iHAS324, LG BH14NS40


  7. #7
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    May 2004
    Thanks again and thanks for the info on the motherboard using 5v for the cpu. I had though I had read that somewhere and then couldn't find out for sure. Thats a little less load on the 12v and its got lots of 5v to spare.

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