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PSU not enough for graphics card?

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Pentium100:

--- Quote from: Temuthril on September 16, 2010, 10:45:25 AM ---I bought a GTS 250 recently, and it says this on the package:

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Minimum 550W or greater system power supply (with a minimum 12V current rating of 24A).
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My PSU is 450W though (Huntkey V-Power 450W), and if I understood correctly, it only gives 18A on 12V. On Windows everything works fine, but occasionally when playing Starcraft 2 the whole computer can freeze up. Should I be worried?

--- End quote ---

Short answer: yes.

Longer answer: When you are not playing a game and just idling on the desktop, the video card enters low power mode and draws much less current than it does when you are playing. In addition, your CPU or CPUs also draw more power when in use 100% than when in use 1% and running at half the frequency (most of modern CPUs can reduce their speed when not in use to save power). So, your computer uses less power when idle than when playing a game, so your PSU is enough for staying idle.
However, when you in fact do start a game and your video card and CPU start drawing too much current for the PSU, a few things can happen:

* The overcurrent protection kicks in and the PSU and your computer turn off.
* The overcurrent protection does not kick in and the PSU releases magic smoke.
* The PSU blows up. It may or may not take your computer with it.
* The PSU manages to supply enough current but the voltage drops below acceptable limits resulting in:
*
* Freezes/reboots.
* Burned out components.
Now, a google search on your PSU leads to this review of a higher power version of the same PSU. That power supply burned when the reviewers tried to pull its rated power, which means that your power supply is not even real 450W. Some manufacturers write the peak power (the power that it can provide for a few seconds) on the box, instead of continuous power (power it can provide indefinitely), just like PMPO rating on cheap audio devices.

Temuthril:
Thanks for the replies, looks like I'll be buying a Corsair VX550W next week.

rostheferret:
I'd make an addition, but it seems you're evading the issue so its more for anyone else planning on upgrading. PSU's can be tricky; some less reputable manufacturers claim "1000W" and the like, completely ignoring the amp requirement (the larger the number of amps it can handle, the more stuff you can plug in, in lay mens terms), splitting things up to a ridiculous number of rails (say its rated at 20A over two rails. That's 10A per rail. If one rail has too much on it, say goodbye to the PSU and possibly anything on that rail).

For anyone else thinking of doing something with their PSU, don't fuck around with unknown brands, fork out for a reliable one; they don't give you more connectors than you can use without blowing something. £20 for a better PSU is far cheaper than replacing your mobo/graphics card when the cheap one overloads and fries everything. Corsair are good, but look to see what you need; I know the 650W has something along the lines of 10 Molex connectors (plugs into fans), 8 SATA (plugs in HDDs/CD/DVD-RW) and 2 PCI-e. Unless you're running a beast or simply want to make sure you have room to add stuff later, it might be overkill. Then again, they'll last longer than any other component in your PC. *shrugs*

Pentium100:
Usually the cheapest device is cheapest for a reason. The most expensive one may be just paying for the brand, gold plated case or something else that does not affect the function, so, if you cannot find reviews etc, you should buy the middle device.

As for power supplies, they are usually more difficult to replace and always require a shut down (unless you have redundant power supplies), so I try to buy reliable ones, so that I don't need to replace them that often. Also, when you buy a power supply, look for one that has fan(s) with ball bearings. Fans with sleeve bearings will fail soon and then you will have the pleasure of opening your PSU and replacing the fans.

If you care about power usage, then buy a PSU that has twice the power (continuous power) than your computer actually uses. Switching mode power supplies have their highest efficiency at around 50% load.

tomoya-kun:
Buy a 750 watt in case you want to SLI later, I needed a 750 for my GTX 260 SLI

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