How much money would you save. Jumping from a 80% psu to 90% psu.

marc512

marc512

marc512

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I was looking at the new coolermasters PSUs which are 90% efficient. It got me wondering.

Would spending £115 on a 700w PSU save you any more money than spending £77 on a ocz modxstream 700w psu?
Then again people do want a high efficient power supply. But would it save you anything on your electric bills?
 
10% extra draw, so an extra 70W being drawn.

Over a year if you say your PC is on 12 hours a day that's

0.07 * 12 * 365 = 306 kWh

306 * 0.13 = £39.78

As rough fag packet calculations.
 
Plus the 80% supply would produce more height and need to have it's fan running faster.

I suppose in a real world situation where you typically draw 150-200w at idle for 11 hours a day and 400w for 1-2 hours a day the savings won't be quite so high but will add up over the life of the PSU making it a better buy. Even 10w/hour saved will save you money given enough time.
 
Makhaira said:
10% extra draw, so an extra 70W being drawn.

Over a year if you say your PC is on 12 hours a day that's

0.07 * 12 * 365 = 306 kWh

306 * 0.13 = £39.78

As rough fag packet calculations.
Click to expand...

Only if it's running at 100% load the whole 12 hours. For real world usage call it a tenner saved, if that. So the more expensive PSU pays for itself in 4 years. That's reasonable I suppose if you'd keep a decent PSU that long. Of course you also get to feel good about saving the planet.
 
It would depend how long you have your computer on in order to be worth it. For casual user who just uses computer for few hours a night, it would take a long long time to repay itself.
 
Heavy usage, it might be worth it, but not because of savings. You are really paying for peace of mind with better components etc.

Unless you are maxing out the PSU, I really doubt you'd make back the money in any reasonable time scale.

Bear in mind that it won't always have 90%+ efficiency, it depends how much you are drawing at any particular time. See manufacturers specs.
 
cheers :) if the 2nd poster is correct and you would save £40 a year. You would need to use that same psu for 2-3 years for it to pay off if current electric bills stay the same. meh thats nothing for some people so it could be worth it.


scougar wouldnt it depend on the hardware aswell? i dont think they will accept a contant power draw. could rise or lower even when pc is idleing.
 
As above, my figures were fag packet. Other considerations are:

1) Most PSUs only hit their best efficiency operating in a small window of their output, usually around 70-80% of their rated output.
2) I assume you're running it at full load 100% of the time (which is going to be a lie really unless you're helping out on a farm project)
3) You might laugh at this, but it's particularly applicable in smaller houses - having a PC throwing out a shedload of heat makes you less inclined to knock the heating on. So you might save (an admittedly small amount) elsewhere.
4) Reserved for all other things that are probably perfectly valid that I haven't thought about :D
 
Makhaira said:
10% extra draw, so an extra 70W being drawn.

Over a year if you say your PC is on 12 hours a day that's

0.07 * 12 * 365 = 306 kWh

306 * 0.13 = £39.78

As rough fag packet calculations.
Click to expand...


Thats assuming a 700w load... load may be only 450w which makes the saving per year of a lowly £25 odd a little pointless for the outlay of the psu.


Andy
 
You really wouldn't see any difference in regard to saving money... now better quality/reliability, cooler running, etc. is another matter.
 
Tbh £115 is quite good, my 600w seasonic cost me £125 4 years ago when 85% was the best at a "reasonable" price. Greater efficiency = less heat=less fan+save a few quid. Just make sure the psu you buy has a good fan, it's the only moving part meaning it's most likely to fail and unfortunately quite a few of the better brands (including a couple of seasonics lines) skimp on them.
 
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