Going from a 85% to a 90% effecient PSU worth it?

[videobruce]

How much actual wattage drop with a given PC going from a 85% efficient PS (rated at 600w for example) to a 90% efficient supply? IOW's when measuring the AC current at the wall, using a 600w rated supply as the example, how much less wattage could I expect? 5, 10, 15 watts?

Is the extra $$ worth it?

 

[EarthDog]

Do the math...

How much do you pay for your electricity (Kw/H)? How many hours do you run your PC?

With that information, you should be able to figure out exactly how much it can save you. The reality is, not much. If you NEED a new PSU, get the most efficient one with a reasonable price tag, sure. Otherwise, just spending say $80 will likely take YEARS to recover unless you are F@H or something of the like where you are running 24/7.

 

[Bobnova]

Average computer at idle is maybe 100w, average computer at load we'll call 350w internal load, though that's reaching. 350w with 85% means 411w, 350w with 90% is 389w, so a 22w savings.
If your computer is at full load 24/7/52 that means you'd save ~192.72 kWh for a year, given the $0.13/kWh energy rate here in my area that means you'd save $25/year.
On the other hand, if you turned your computer off for the 7 hours you're asleep instead of running it full bore, that'd be a yearly savings of $134.
Again this assumes it runs full load all the time, which it does not.


In short, it's not worth it unless you're already replacing your PSU for some reason and gold/platinum doesn't cost much more.

 

[videobruce]

Forgetting the $$ saving, using that 100 watt PC as the example, which is what mine draws as it is now (before rebuilding), how much decrease in wattage from a older 80plus supply (before those current standards were written) shoyld I expect at 85%, then at 90%?

(I clarified the OP)

 

[EarthDog]

That amount of power your PC uses? None. Its how much it takes from the wall that will be different.

Again, do the basic math. If you have a 100W load at the wall and gained 5% efficiency through the PSU, you would be pulling 95W at the wall (again the PC will be using the same amount of power).

 

[Bobnova]

Take the internal draw (100) and divide by the efficiency.
100 / 0.85 for 85%
100 / 0.90 for 90%
That gives you an estimate for wall power used.