PSU Sizing

[ARod]

There are a couple of different schools of thoughts on PSU sizing.  However, one thing I've noticed across the different sites is how they all rate their efficiency versus the load.  If you look at the graphs they offer with all their marketing stuff you see that typically the best efficiency is when the PSU is at 50%-60% load.  Not sure if that's just a marketing gimmick to get customers to buy larger power supplies or what.  But, if you follow that rule then you would size your PSU at 80% to 100% higher than what your actual max load will be.

 

 

Does that make any sense at all and what are your thoughts?

[Andi]

no, thats right, at idle you want to be over 20% and under load at 50-70%

 

under 20% is not specified and some PSUs suck really hard at 10% load.

 

The big problem is that many people don't really know how much power a system needs. A Titan with overklocked 3770k needs 300W, so a 500W PSU would be perfect. if you overclock the titan too maybe 550W or 600W..thats all

[Glenwing]

Yeah that's now it is.  You want to choose your power supply to be ~double to what you calculate your power needs to be.  Getting "just enough" power isn't a good idea, running your power supply near 100% load is less efficient and puts strain on the power supply.  Plus due to capacitor aging your power supply's maximum power will degrade a little bit over time so you want some headroom for that.

[Hyydrah]

I think it has a lot to do with marketing as well as headroom for future upgrades.