How many watts do I need in my PSU?

Malek Agha

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Nov 3, 2014
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I remember someone saying that you should take the maximum amount of wattage that your build might use, and multiply that by a certain percentage. Then add that percentage to the maximum amount of wattage and that's the sweet spot for the amount of watts your PSU should have. Idk if this is the case or not but regardless I would still like to know how to determine the amount of watts I need.

Thank You
 
Solution


Not really,
Check that Tier List i posted, try to stick to Tier 1 or 2.

They're rated higher for a reason, they're made with better quality materials and have a higher efficiency under load.

A very common thing in PSU is that they are advertised to work at XXX Watts, but in reality then don't even delivery half of it when required.

Those in Tier 1, are all 80+ Bronze, Golden certified. That mean they have at least 80% of their capacity proven to be real.
The higher the 80+ the better the PSU. Always go for that 80+ sign, if it doesn't even have one don't even go near it. That's my advice.
That will work. Basically PSUs are setup to have their highest efficiency between 50-80% load.

So for a system with a 300W draw, a 500 or 550W supply is best. This means it isn't underloaded and inefficient (or out of spec) and it isn't running near its maximum where the fan has to run at full speed and it once again becomes less efficient.
 
yah 80-85% of max load is ideal "sweet spot" for psu usage. having more won't hurt anything but having less will shorten the lifespan of the psu some by running it at high loads all the time.

so add up the wattage of all the parts and then divide by .80 and .85 (80 and 85%) to get the power range that is ideal for you. then consult the psu tier list above and chose a quality psu. a cheap generic unit is as bad as it gets for a pc. spend the extra money and get a quality unit. if you're not sure, then just ask and we can point you in the right direction easy enough
 
not really a very good psu. check this one out

PCPartPicker part list / Price breakdown by merchant

CPU: Intel Core i5-6500 3.2GHz Quad-Core Processor ($191.91 @ Jet)
Motherboard: MSI B150M MORTAR Micro ATX LGA1151 Motherboard ($75.28 @ Jet)
Memory: Team Elite Plus 16GB (2 x 8GB) DDR4-2400 Memory ($84.99 @ Newegg)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($49.78 @ OutletPC)
Video Card: XFX Radeon RX 470 4GB Triple X Video Card ($179.98 @ Newegg)
Case: Corsair 200R ATX Mid Tower Case ($57.99 @ NCIX US)
Power Supply: Rosewill 650W 80+ Gold Certified Fully-Modular ATX Power Supply ($39.99 @ Newegg)
Optical Drive: Lite-On iHAS124-14 DVD/CD Writer ($16.89 @ OutletPC)
Monitor: HP 22cwa 21.5" 1920x1080 60Hz Monitor ($115.42 @ Amazon)
Total: $812.23
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-12-06 13:07 EST-0500

more power than needed for sure but gold rated, fully modular and high quality. plus it a great price right now with $30 rebate
 


Not really,
Check that Tier List i posted, try to stick to Tier 1 or 2.

They're rated higher for a reason, they're made with better quality materials and have a higher efficiency under load.

A very common thing in PSU is that they are advertised to work at XXX Watts, but in reality then don't even delivery half of it when required.

Those in Tier 1, are all 80+ Bronze, Golden certified. That mean they have at least 80% of their capacity proven to be real.
The higher the 80+ the better the PSU. Always go for that 80+ sign, if it doesn't even have one don't even go near it. That's my advice.
 
Solution


I guarantee every PSU in tier 3 and probably tier 4 is capable of ~120% of its rated wattage,
 
The rating system isn't about capacity, but efficiency. Capacity is determined, in part, by efficiency, cooling, and the ratings of the internal parts.

80+ means at least 80% efficiency in converting the input power to output power, at 3 different load levels 20%, 50%, and 100%. If your output is 500W and your efficiency is 80% that means you are wasting 100W as heat so the input is roughly 600W. (I'm rounding so I don't have to get out the calculator)

Gold/Platinum/Titanium supplies break into the 90% efficiency at 50% load, so they waste half as much power and run that much cooler compared to 80+ or un-rated supplies.

But to get that efficiency they generally have higher quality parts. You do see low tier supplies with Bronze ratings, they can pass the tests, but aren't that reliable or long lasting.
 

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