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How does Power Supply Work

I'm building a system right now and came to a halt when i realized my video card required 400 watts. I have a 500 watt power supply. Does power supply stack or does it share? for example my cpu requires 95 watts so does it stack as in the total wattage being 495 or is the power supply shared as in it considers the wattages individually?
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More about power supply work
  1. When your PSU says 400W, it is talking about the whole system, not just the GPU. This includes the CPU, hard drives, DVD, etc., so you'll be fine with a 500w PSU.
  2. tecmo34 said:
    When your PSU says 400W, it is talking about the whole system, not just the GPU. This includes the CPU, hard drives, DVD, etc., so you'll be fine with a 500w PSU.

    I'm sorry I'm not quite understanding you although you say it'll be fine. For clarification I have a 500W PSU and the video card is saying it requires 400W. My concern was whether or not the power supply will able to support the rest of the computer if the video card is taking up 400W. Am i supposed to add all the wattages required and see if it falls below 500W? or is the 500W just stating that that is the max for each peripherals I am adding? I'm also not understanding when you say it's talking about the whole system. If it's not too much to ask would you be able to elaborate on that? To help you further i'll list all the parts that I have so far

    *BIOSTAR A770E3 AM3 AMD 770 ATX AMD Motherboard
    *AMD Athlon II X3 450 Rana 3.2GHz Socket AM3 95W Triple-Core Desktop Processor ADX450WFGMBOX
    *CORSAIR 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333 Desktop Memory Model CMV4GX3M2A1333C9
    *Rosewill DESTROYER Black Gaming ATX Mid Tower Computer Case
    *WD Caviar 500GB Serial ATA HD 7200/16MB/SATA-3G
    *SAPPHIRE 100293DP Radeon HD 5570 1GB 128-bit DDR3 PCI Express 2.1 x16
    *Thermaltake TR2 W0379RU 500W ATX 12V v2.2 Power Supply
    *And some generic CD-Drive
    *And a few 120 mm fans
  3. hi again

    I checked this forum:
    and i looked at my video card and it said peak 3d is 76W so i'm confused as to why the box label says 400 Watt power supply?
  4. oh wait...i think i just answered my own question...

    I just interpreted the wasn't saying 400 watts was the required power but asking for a 400 watt PSU or greater

    I feel like an idiot

    thanks for the post however
    Much appreciated
  5. Use the 76 Watt figure when calculating the total power requirements of your complete system. AMD is just recommending that you don't use a power supply that isn't capable of producing at least 400 Watts.
  6. Best answer
    (1) The 400 watt PSU is a recommended min for the whole suystem. The cpu and video card use the most power followed by the Ram and the MB.
    (2) Your system will use less than 300 Watts, so unless you plan on a new Graphics such as the 5800 series a GOOD 400 Watt PSU is fine. I currently use a corsair 400 Watt PSU with my wifes computer (i3-540 and a 5670 graphic card.
    (3) there are many low cost 500 watt PSUs out there thare are simply put JUNK - In the DON'T buy catagory.
    a reall good supply woud be the corsair 430 W @ Approx $41
    and a 500 W corsair @ $56

    There are other good supplies, just make sure you can find a review (google it) for what you are looking at - DO not got just by newegg custumer reviews.
  7. Best answer selected by sykoseki.
  8. This topic has been closed by Maziar
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