Hardware: DIY Power – How much?

In building my new computer I needed to verify my calculation of the amount of power required. What size power supply do I need?

By my, mostly in my head, calculation as I selected parts I need 500-550 watts at peak demand. I select a continuous supply rating based on my anticipated peak demand. While power supplies have built in the ability to handle peak loads that exceed their continuous rating and that often gets advertised, that ability usually comes from considering what all the parts can stand when pushed to >100% of their design spec.

Computer Power Supply

Computer Power Supply

Humans can walk all day at 5 mph. But, we can only run at 20 mph for a few minutes. Sort of the same thing with computer power supplies. At some point in time they overheat or an individual component overheats by too much and the unit fails. Some units have anti-self-destruct protection, which reduces the power supplied to save itself. And what does that do to the rest of the computer? Nothing good. 

I’ll also add some room for growth, more fans, bigger M.2 SSD, additional spinning drives, VR headset, more USB devices, …

I have mostly used ASUS’ Power Supply Calculator to check the power demand for all the components I have or plan to have. But ASUS’ is out of date. There is no i5-6600K nor a GTX1060. The newest video card they had was an Nvidia 700 series. Crap. Looks like waiting for an update is well beyond my patience. Several others I checked stopped with the Nvidia 900 series cards.

I have found OuterVision’s Power Calculator. They include my i5-6600K and GTX1060. Their calculator is the most up to date I found. It also has the RX460, 470, and 480 cards included, which means it has been updated very recently.

I didn’t go nuts looking for the best calculator. So, this isn’t a complete review of all the calculators. It is just the first one I found that works for me. If you have found others, please put a link in the comments.

The tool is there for the Computer DIY crowd. It seems the users contribute to keeping it updated. I imagine that means this will remain the most up to date calculator around.

Second Life Power Supply Demands

Do we need to consider anything special about computer power supplies for use with Second Life? Not really.

About the only somewhat special consideration I can imagine is from people playing a game for hours. One could get by on a smaller and cheaper power supply by counting on its ‘peak’ load rating.

With Second Life we may drive various components to max demand and hold them there for hours. Power supply designers consider peak demands transient, short duration demands. So, if one runs a power supply in that ‘peak’ range for extended periods, eventually that will catch up with us and the unit will likely fail early.

There is a difference between ‘maximum’ and ‘peak’. Designers design for maximum and build with parts that can sustain maximum demands indefinitely. Peak demands are something the components can supply by exceeding their maximum operating parameters for brief periods.

I prefer to buy a unit sized to provide my peak demand as its continuous rating. It costs a bit more but, I seldom have to deal with a power supply failure.

PSU (Power Supply)

PSU (Power Supply Unit)

Depending on the components Second Life is going to be a REALLY BIG load on the system or a moderate load. That is true of any game. A big load drives components to consume their maximum power requirement. If the power supply was selected to carry the maximum demand, all is good regardless of how long it has to work that hard.

The maximum continuous power we need to supply can be determined from OuterVision’s Power Calculator. I add in all the future hardware I think I will ever add. To that size I add 100w for what I haven’t imagined and I hope to extend the unit’s life by running at less than 100% of its output even at peak loads.


Then there is overclocking. Overclocking means we speed up the computer’s processing clock. I’ll explain all that another time. The TL:DR explanation for power consumption and overclocking is it increases power demand. The computer has to do all its work in less time, meaning it does more per second and uses more power. OuterVision’s calculator allows you to include overclocking in the calculations.

2 thoughts on “Hardware: DIY Power – How much?

  1. One consideration is power supply efficiency. Rating systems help but peak efficiency is achieved well short of peak output. It is always better to buy a bit more than you think you need.
    Another consideration has to do with the computer case. All my cases for probably 10 years have had the power supply positioned so it draws air directly from outside the case. The best such cases also have a filter on that air input. Positioning the PS with the fan facing inward is a relic from the days (30 years gone?) when the fan in the PS was *the* computer fan, we can do much better today. I have not had a power supply failure since I started buying cases like that.

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