How to determine if a PSU is enough?

Hello everyone,

I just finished putting my first built together this afternoon and tried it out. Everything installed great and successfully. Anyway, I went to the asustek website that provides you with the general idea of what the minimum wattage of psu you should get based on what you choose from the drop down menu.

Here's my result:

Minimum: 600W

My new built

I have a 650W installed right now and it's been running fine for the last 3 hours. My question is: How will I know it's enough? I haven't plugged in the 3rd hard drive just yet because I mainly wanted to install the OS first and make sure everything is okay. I just want to be sure because I've read everywhere that you can never tell until your computer randomly shuts down or something. I have my eyes on a 850w and if it'll be safer to upgrade to that, then I would go ahead and buy one.

Thanks in advance!
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More about determine enough
  1. You are totally safe. I use the [url= and I took what was in that pic of yours and put that into the antec one and it gave me 452Watts, and that was putting in 3 hard drives and a bunch of fans
  2. You are safe as long as the PSU is a quality one.
  3. Hey, heres a Tom's article about the PSU needs of a PC...look through it and you should be able to determine if urs is up to the task:,2122.html
  4. Best answer
    The website has grossly overestimated the power requirements of your system. Even a quality 500-550 W PSU will be enough for your current system. Add another 100 if you go crossfire.
    This means that your current 650 W PSU, assuming it to be of a good quality, is more than enough.
    There's definitely no need to get an 850 W psu. It could run two rigs like yours :pt1cable:
  5. Thanks guys.
    Yea, I used another site before but forgot what it was.
    Well, so far it's running good with the power supply I got. It's not Antec or anything but this is the same PSU as I got from my other Cooler Master build and that's been running well for 4 months now.

    What happens when a psu fails on you? I mean so far I've had good luck with power supplies even with prebuilts. I'm just curious.

    My rig in the picture:
    Antec 300 Illusion
    MSI 790x-g45
    Phenom 945 (no OC)
    Adata 4gb pc12800
    Radeon 4850 (not installed when I took the picture)
    3 - 500gb = 1.5tb HDDs
    and altogether 4 fans running on medium speeds.
  6. VX450W is enough. Even my PC has almost similar config. except that i have Intel E8400 and mine works on that PSU. Don't worry.
    And other than the PSU calculators, best place to find out about the PSU you need is this forum!! Just ask!
  7. When deciding how much wattage you will need for your system, it is often a good idea to have a look at the manufacturer's data for the graphics card since this is the most power-hungry component in a modern day system. These details can be found at the manufacturer's website. For example, your card the Radeon HD 4850 has the following recommended power requirements:

    450 Watt or greater power supply with 75 Watt 6-pin PCI Express® power connector recommended (550 Watt and two 6-pin connectors for ATI CrossFireX™ technology in dual mode)

    These requirements apply to the whole system not just the card and often give a very good recommendation if you're unsure. However, you also have to use a bit of common sense since these will apply to the average system. If you have a large number of HDDs, fans or any other device which draws a lot of power then you would be better off playing safe and getting something a little higher than the recommended. You also have to bear in mind that a PSU is most efficient between 40-60% of its total load so this may also be a factor you wish to consider.
  8. Thank you hell_storm. :)

    @ Moody:
    Thanks for all the info. I already had the extra 650w so I'm just putting that in and like I said, so far everything is running right. I would definitely upgrade it to a 850w at least when I decide to get another graphics card and crossfire.
  9. Best answer selected by myoffive.
  10. Quote:
    What happens when a psu fails on you? I mean so far I've had good luck with power supplies
    even with prebuilts. I'm just curious.

    Problems range from harmless random system crashes to a burnt PSU due to spiking voltages which cannot be tolerated by the failing psu.
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