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Got a new XFX GTX260^2 video card. The only problem is the "Minimum power" is 500W on the box. I've got a Chieftec 450AA PSU with just a minimal number of attached stuff (1hdd, WD green; 6gb (4module) ram; dvd writer).

Bought a cable for the 6pin power input on the card. Got picture, works in every aspect. Still. Should I get a new PSU (like a Corsair or Antec 600W)? Will the card perform slower with this PSU?

(Yeah the last part is a particular question but in I'm also asking in generic. I was wondering about this so many times and I hope we'll put and end for this question for once and for all.)

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Okay guys answering here: Will get a Crysis demo to try it out. Source based games run fine but they are not really gpu extensive I guess. –  Shiki May 31 '10 at 15:43
    
Okay guys both were perfect answers, however I cant accept both, sorry. My card is running fine, tried BOINC, furmark, games, everything works perfectly, no problem whatever. Thanks again. (Glad it works. A normal PSU is NOT cheap. :/) –  Shiki Jun 2 '10 at 19:40

2 Answers 2

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The "recommended power supply" with graphics cards is somewhat accurate, somewhat misleading. When they make that estimate, they are assuming some basic computer setup, which may or may not match yours. You seem to have a fairly basic setup, so that recommendation is probably fairly accurate.

The best place to go these days for a good estimate is PSU Calculator - Take that value and give yourself some headroom when looking for a new power supply.

GTX 260's draw about 150W under full load, and depending on your processor, it can draw that much or more. (Not sure what the ^2 is, are your running in SLI?) 30W for motherboard + 130W (core i7, just using for estimate) for processor + 150*2 for SLI GTX 260's = 460W, and that doesn't include USB periphrials / harddrive / ram / optical drive.

The card won't run slow if you overload your PSU - The system will simply freeze, blue-screen (or your OS's equivalent), or crash. And it may work fine until you load up a particularly intensive game. It may run for most games and only show problems if you stress-test the system. This shouldn't damage anything outright (nothing will explode in a flaming ball of fire), but it's never "good" to run components on the edge like that, and you do risk the contents of your harddrive when an unexpected shutdown occurs (less these days than in the past though)

To simplify, grab yourself some Crysis or Supreme Commander and see if your system freezes or crashes. If it does, or if you want to make adding a harddrive a worry-free process in the future, go ahead and pick up that 600W power supply. (Remember, the power supply rating is the max, not how much your system will draw, so you're not going to waste power by getting a power supply that's bigger than you need)

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When a PSU (Power Supply Unit) is under the minimum requirements, in current (Ampere) distributed by its lines (12V specifically for videocards) or more in general in availabled Watts, it could lead to different problems, artifacts, unexpected shutdown, unexpected crashes of games, etc.

Many times on the video card boxes the manufacturer "lies" asking Watts that are not really needed to avoid problem because also many PSU "lie" about their real potential. :D

In your case could be that Chieftec PSU (that is not bad) could be enough for GTX260x2. Not really sure without trying. You can do some tests, run a video/cpu stress test on your system and look if you have any problem.

In any case a VX-550 Corsair should do the work quite well.

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