Need help understanding PSU efficiency, want to get another PSU.

[bleucharm28]

So if you look my signature, i am currently using a 1200w PSU. Which is an overkill for my setup even in SLi. I bought this way before GTX 680's came out. Couple of reasons. I bought it because i thought i would be powering 2 OC'd nuclear 480's, and CPU 920 like no tomorrow, in water. A friend of mine made me an offer i couldn't resist not buying this PSU for only $150 bucks.

Let say i get like a 750W which should be enough for my setup, (according to Power Supply Wattage Calculator) So just how much energy am i saving? If i were to leave computer running 24/7 vs 1200w

But in reality, my computer system shuts off within 1 hour when not in use. It come back on when I move my mouse or keyboard.

Thanks

 

[TemjinGold]

The biggest savings comes from the price of the unit. Since you already bought it, there's not too much sense in swapping now.

 

[Ketchup]

What matters is the efficiency of the PSU running at a particular output. Generally, buying a PSU with way more wattage than you need will keep you on the lower end of the PSU's power delivery scale, where the lowest efficiency lies with most PSUs. So ideally, you would want a PSU delivering just above the max power draw of you system, with a good 80+ efficiency rating, and from a reputable manufacturer. Depending on where you live (referring to cost of electricity), the noticeable difference may be next to nill.

 

[bleucharm28]

Thanks peeps!

 

[Torn Mind]

What matters is the efficiency of the PSU running at a particular output. Generally, buying a PSU with way more wattage than you need will keep you on the lower end of the PSU's power delivery scale, where the lowest efficiency lies with most PSUs. So ideally, you would want a PSU delivering just above the max power draw of you system, with a good 80+ efficiency rating, and from a reputable manufacturer. Depending on where you live (referring to cost of electricity), the noticeable difference may be next to nill.

Usually, the PSU is most efficient when DC power draw is one-half of its rated capacity, i.e 180 watts DC for a 360 watt PSU.

 

[Ketchup]

Usually, the PSU is most efficient when DC power draw is one-half of its rated capacity, i.e 180 watts DC for a 360 watt PSU.

Yes, many modern PSUs will hit their top efficiency at about 50%, but the drop above that is minimal, vs the drop below that which can be quite substantial in comparison.

 

[lehtv]

Yes, many modern PSUs will hit their top efficiency at about 50%, but the drop above that is minimal, vs the drop below that which can be quite substantial in comparison.

True but only below 20%. 80Plus standards have the same efficiency requirements for 20% as for 100% load, so between that range you're going to see good efficiency as long as the unit is 80Plus certified.