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Does it matter what size power supply I use?

post #1 of 5
Thread Starter 
All things being equal, does it matter what size PSU I use?

Let's say, for instance, I have a system that uses 500w during peak usage:

- If I have a 550w psu or a 1000w psu, made by the same manufacturer, with the same specs (aside from one having more capacity) will they perform the same and will they have the same power draw?

My assumption is that a 1000w unit can pump out 1000w but will only pump out what the system demands of it. So if a system idling uses 200w and at load uses 500w the psu would pump out 200 and 500 watts respectively in those cases.

- Is my assumption correct?

Another way to ask the question is if I run a system with a 550w psu and I run the same system with a 1000w psu (assuming I do everything the exact same) will they consume they same amount of electricity and provide the same amount of power?

Thanks ahead of time.
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post #2 of 5
The powersupply will only give out whats used, so if you have a oversized PSU it will not use any more power than a lesser one.
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post #3 of 5
Quote:
Originally Posted by ventac View Post

All things being equal, does it matter what size PSU I use?

Let's say, for instance, I have a system that uses 500w during peak usage:

- If I have a 550w psu or a 1000w psu, made by the same manufacturer, with the same specs (aside from one having more capacity) will they perform the same and will they have the same power draw?

My assumption is that a 1000w unit can pump out 1000w but will only pump out what the system demands of it. So if a system idling uses 200w and at load uses 500w the psu would pump out 200 and 500 watts respectively in those cases.

- Is my assumption correct?

Another way to ask the question is if I run a system with a 550w psu and I run the same system with a 1000w psu (assuming I do everything the exact same) will they consume they same amount of electricity and provide the same amount of power?

Thanks ahead of time.

yes, even assuming everything equal, the watts actually matter.

u dont want something thats to powerful, but weak also.

PSU's are ideal and most efficient at 40-60% load.
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post #4 of 5
Quote:
Originally Posted by IMKR View Post

PSU's are ideal and most efficient at 40-60% load.

This. However, you do not want to aim for this unless your system is running at max load 24/7. Smaller PSUs are generally more efficient at lower watts compared to their larger, more powerful counterparts. If your system is pulling 550w, I would recommend a 750w PSU since that gives you ample headroom to overclock, swap hardware, and will be in an ideal band of efficiency for the longest possible time.
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post #5 of 5
Thread Starter 
Thanks guys.
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Dark Water
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i3 530 H55-USB3 GTX 260 G.Skill Ripjaw 2x4gb 
Hard DriveOptical DriveOSMonitor
WD Caviar Black 750GB Samsung DVD-RW Windows 7 Ultimate 23" Acer X233Hbid 
KeyboardPowerCaseMouse
G15 OCZ ModXStream-Pro 500w Custom Lian Li PC-71 G9 
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