Upgrading PSU, how does a computer handle changes in power?

Sorry about the nooblet question, but I'm a bit new to the build-community.

From what I understand you always want to aim for a more powerful PSU than what you have in total required power consumption, if all my components need 567 W, I'll want to aim for 600 W or higher. But what if I currently have computer pieces that consume say... 220 W, and I want to upgrade to something much bigger in the future, but I'm buying the pieces periodically. Suppose I bought myself a nice big 800 W PSU, and plugged in my old components. Would it... damage anything, using such a big power supply to feed such small demands? Is it possible to over-compensate too much?
6 answers Last reply Best Answer
More about upgrading computer handle power
  1. what is system spec CPU + VGA ?
  2. Nope, though an 800W psu would not be very efficient running only 200w .. whats an extra half penny per hour on the utility bill...

    The PSU would only create what was needed to run much like a light bulb only gets what it needs from the wall outlet.

    Just make sure you get a quality PSU, a cheap 800w unit might not make 500w in real life. Jonnyguru is a nice site for PSU reviews.
  3. Well, right now I'm using a low-profile Acer tower, CPU is a dual core (Athlon II X2 220), and the graphics come from a NVIDIA GPU 9200 chip that's hidden somewhere on the motherboard. The current PSU has 220 W.

    I want to upgrade piece by piece, and I'm probably going to start with the case and a new PSU. I was just wondering what would happen if I took all the innards of my current computer and plugged them into my new setup. I'm probably going to want much more than 220 W for everything I plan on adding.

    @ popatim
    I've been watching youtube video reviews from NewEgg recently... they seem reasonably good. Though I just realized they might be biased since they review stuff they want to sell you. Not sure. I'll check out that site you mentioned though, thanks.
  4. - New Seasonic SS-300SFD SFX12V (V3.1) 300W 8cm Fan Rohs 80+ Bulk Popular High Quality

    - Antec Earthwatt 380D enough
    - Corsair CX 430W
    also if you can find this PSU it's good choice too is AKASA esentsial 300W :
  5. Best answer
    As far as PSUs are concerned, be informed. Before you buy any PSU read accurate, objective PSU reviews at reputable sites such as or on the EXACT model PSU that you are interested in as some brands have good and poor quality PSUs.

    You can also get an accurate rating of how much PSU power is required for your current or future system at the PSU calculator link below. Once you know the total PSU watts required then you need to confirm that the 12v rail has enough amps. to support your Vid card(s) and the rest of the PC system.

    There are several websites that show the Vid card power consumption in watts. Divide the watts by 12 to determine the amps. required on the 12v rail(s). Add 15 amps for the rest of the PC on the 12v rail and you now know the Minimum total 12v rail amps required under full load. It's best to have at least 5-10 amps. reserve on the 12v rail available under full load so the PSU is not loaded to 100%.

    It's also worth noting that people often misunderstand the 80% power rating. This is a rating of the PSU's energy efficiency not it's output. 80% plus PSUs use less grid power to produce the same PC power. If it's 80% Bronze, Silver or Gold the cost savings on electricity is pretty small between Bronze, Silver and Gold unless you are paying very high rates for electricity so any 80% rated quality PSU is fine even if not Gold. For those who leave their PC on 24/7 a quality 80% PSU is a good investment.

  6. Best answer selected by PTNLemay.
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