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Maxing out a PC power supply

  1. Jan 11, 2011 #1


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    I currently have a slim-line PC I bought real cheap.


    I paid $200, not bad.

    Well, the case is Custom, as is the internal power supply.

    The video card is lacking, and I know there are quite a few pci-e low-profile cards that I can put in, but the power supply on the PC is only 220W, and a few of the low-profile cards require 300,400, etc.
    (I have a good gaming laptop already, this is just for my girlfiends/home use)
    I know the max ANY video card that I can use is like 150W, but I have no idea on the actual computers load.

    If I get one that "requires" 300W, and I do something intensive, what would happen? Would it just shut off? Would it fry the power supply? Is there a fuse somewhere? Etc.

    Anyone know?
  2. jcsd
  3. Jan 12, 2011 #2
    It would likely not boot. It could fry the supply. It could fry other parts of the computer. Many PC power supplies have gotten so cheap that they don't have circuit breakers or fuses that can be replaced by the user.

    If you don't mind how it looks and you know a little about putting together computers then you might consider taking the side off the case, getting a used but working 450 watt supply, carefully sitting it on top of a box next to the computer, unplug the internal custom nonstandard supply, plugging in the standard supply and using the computer.

    My mother's more-than-a-decade-old computer running her absolutely essential dBaseIII blew a supply. All I had with me at the time was a junk computer but I was able to do what I described above and got it working. It is a dust magnet but it has been working for her for a couple of years that way.

    Be careful if you try this. I wouldn't want to be responsible for someone who didn't know what they were doing ending up ruining something important or valuable to them. If you aren't sure you know enough to do this then ask around to find someone who really knows what they are doing and isn't just saying they do.
  4. Jan 12, 2011 #3
    The depends on the power supply. If you go 50watts over what the PS rated for it will probably be fine. Given its an Acer, if you push it really far the lines will probably start to drop in voltage until the PC artifacts or shuts down.
  5. Jan 16, 2011 #4
    Often, depending on the video card, the card will shut itself down when it detects low power. I know nVidia cards do this, I'm not sure about yours. I'm having a problem along these lines and after the card shuts down it has an led error code that indicates as much. Alas, I must wait to buy a new PS.
  6. Jan 16, 2011 #5

    Vanadium 50

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    It's more complicated than that. A power supply has a limit on the current it can put out for each voltage. These should not be exceeded - if they are, one of three bad things can happen: the power supply can detect the overload and shut down, the voltage can drop making the computer shut down, or the power supply can overheat.

    A 250W supply might be able to put out 20A at 3.3V, 25A at 5V, 13A at 12V, but no more than 250 in total. A high end graphics card is very likely to push this over the top in one or more of these categories.

    I would avoid any video card that required external power. PCIe provides up to 75W, so if it needs external power, it's drawing more than that.
  7. Jan 19, 2011 #6
    Really, you should be able to obtain a 450w power supply for less than 20$. This should solve your problem a lot easier. Even cheaper if you buy used. I recently acquired two 500w ps for 10 each and one caught fire. I will say that it was kind of worth 10$ watching it catch fire as I have never seen that happen before. Anyway, the point is that you could avoid this problem all together upgrading your ps on the cheap.
  8. Jan 20, 2011 #7

    Vanadium 50

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    Except that the present power supply is non-standard. That means it's probably not cheap to upgrade.
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