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Are Gold rated power supplies worth the extra money?(r/buildapc)
Well, lets do some math.
Your CX500 is plain 80plus which means it is rated for 80-80-80% The SuperNova is gold which is rated 87-90-87%.
Lets average the gold to 88% for ease of math, say your computer uses 100 watts on average during the year and electricity costs 12 cents per kwh.
100 watts x 24 hours x 365 days = 876,000 watts or 876 kilo watts.
Multiply that by your 12 cents of power cost and you get $105.12 which is what you would pay if you have a perfectly efficient power supply of 100%. Now, that is the power that the components use, we have to use the inverse of the efficiency to see what that computer would draw from the wall. 80% is equal to 1.25 and 88% is equal to 1.136363636. Which brings a total cost of each to:
Gold PS: 119.45 80 Plus: 131.4
That is a cost per year. So assuming you have an average computer lifetime of 4 years, that is a savings of 11.95 per year and 47.80 over the lifetime of the computer. Your new powersupply costs 90 so it wouldn’t be worth it. However if you were in the planning stages of the build, it would be. Your gold power supply is 90, 80plus is 58. Savings of a gold is 48 dollars which saves you a grand total of 15 dollars by going with a gold power supply.
Please note that the numbers at the beginning were a rough estimate of idle and involve leaving a computer on 24/7. If you have different specs, you can change as needed.
EDIT: Figured I would add this in here if anyone was looking for a lowish cost way to get more exact numbers. You basically plug computer in then do an average day or two of computer use and that should give you a daily average of power use which you can use to extrapolate out. Note if you use the product below, your efficiency conversion needs to be different to account for the fact it is already pulling numbers from the wall.
Edit2: Another thing I forgot to mention as this may be important to some… When a PSU has an efficiency rating of 80%, what that means is that 80% of your power stays as electricity and 20% of it is converted to heat. This means more fan use and more heat. If you want a quieter PSU or need to keep heat down because you are overclocking, a gold or platinum PSU is recommended so that it doesn’t contribute as much heat to the inside of the case.