Power Supplies & Efficiency

[Luckyboy1]

It has occured to me that as power usage for PC's increases, that the efficiency of the power supply in question becomes more important. It would be nice to know how these efficiencies translate into possible savings in Dollars. Anyone have a link to an article on power supply efficiency technologies and whatnot?

Yes, I already Googled without success!

 

[Zepper]

Many PSUs hit over 80% efficiency in their sweet spot (around 80% of max power output). So the key is to get a PSU for your system that will be operating in its sweet spot most of the time. There are lots of sites out there for estimating power usage of a system. But most often buying a quality PSU of over 400-450 Watts will guarantee that it will be operating OUTSIDE its sweet spot most of the time, so it's a waste of money at purchase and over time.

Or you could opt for a Seasonic in the S12 series that generally operate at above 80% for most of their output range. The 80+ organization that is certifying PSUs with above 80% efficiency over a wide range of outputs should have info and links re. cost savings (but be wary as they have a dog in the hunt and or an agenda so their info may be tainted). The active PFC feature may also contribute to thr price you pay to operate your system.

.bh.

 

[Luckyboy1]

I think you're on to my line of thinking here Zepper. Computers used to use little power and it wasn't a big consideration in your annual electrical bill. However, now that the power needs are like 3 times what they were 10 years ago, it got me wondering about the whole "worth it" thing as far as operating costs vs. not only percentage of power used by the supply and how efficiently it does it, but how total case cooling can affect the costs of running your PC. The question in my mind is when is the power supply big enough to put it back in its sweet spot as far as performance goes from both an operating temperature and overall efficiency?

Also, a few years back they were talking all the rage about solid state transformers and how they'd be more efficient, yet I've not seen any offerings of solid state transformers in PC power supplies; I wonder why?

 

[rise]

Originally posted by: Luckyboy1
It has occured to me that as power usage for PC's increases, that the efficiency of the power supply in question becomes more important. It would be nice to know how these efficiencies translate into possible savings in Dollars. Anyone have a link to an article on power supply efficiency technologies and whatnot?

Yes, I already Googled without success!

well, i recently switched one rig to an 80+ cert psu- the seasonic 400htt. i was hoping to get both rigs on it but it doesn't like my main rig, for one reason or another. may be the dfi compatability or just overpowered.

at any rate, i was thinking i could save $5-10/mo (plus the $5 coupon i get from nstar, lol) by switching. my reasoning, which i think is accurate was-

i run my rigs 24/7 full load (dc projects). my apc ups shows i draw up to 365w. using a tpII550, i might get 75% efficiency, probably 70% iirc from spcr at that load. but lets use 75%. so my rig is actually using 260w.

so if i can get 85% efficiency, which iirc is what spcr said the seasonic reached, i would only need to draw 310w to maintain that same 260w for my components.

at .10/kwh x 50w saved per hour i think gives me that $5-10/mo.

anyway, for me, it was oin the heals of yet another staggering electric bill that i decided to try it. we'll see what happens. at least i feel like i'm trying

 

[Luckyboy1]

I just got off the phone with technical support over at PC Power & Cooling. He says you lose efficiency if you go too low in usage and you also lose if you go above 85% of the power supplies capacity. He went on to say that case temperatures in the area where the power supply is at should not be over 40 C to keep from losing efficiency as well.

 

[GalvanizedYankee]

Originally posted by: Luckyboy1
I just got off the phone with technical support over at PC Power & Cooling. He says you lose efficiency if you go too low in usage and you also lose if you go above 85% of the power supplies capacity. He went on to say that case temperatures in the area where the power supply is at should not be over 40 C to keep from losing efficiency as well.

What he is saying is true, based on my study on this topic. Zippy/Emacs rates thier efficiency at full output and operating temp. So on the spec sheet it looks low when compared to providers that rate at 25C in the "sweet-spot." I do not think Seasonic does this however. jonnyguru.com and several others will indicate efficiency at a number of given outputs in load testing of SMPSs.

PSU efficiency is a hot topic and as such becomes a marketing tool. For me it is of secondary concern when selecting a PSU because stable, clean output is primary.



Off your topic, but maybe of interest re.solid state componets, like transformers.

Note the metal MOSFETs in this board review(hate mommaboard because it sounds ignorant)
http://www.techpowerup.com/reviews/Cebit2006/Day3

Solid state capacitors http://www.endrich.com/products/p_capacitors_poscap.html


...Galvanized

 

[furballi]

Most AMD rigs will pull between 120 to 180 watts of actual power. Add another 50 watts for Intel PCs. The majority of PSUs will often reach peak efficiency around 40 to 60% load range. Therefore, a quality 350 watts PSU would be the ideal PSU for an AMD rig. I'd go with a 400 unit with an Intel CPU.

Most Dells and HPs come with a good 350 watts PSU. This is not because they want to save $ on the PSU that could result in pre-mature system failure. There is no need to over-spec if the system does not need the extra power!

So how can an average person identify a quality PSU with good efficiency? First measure the 12VDC rail at the molex pin at IDLE and FULL LOAD with all the bells, whistles, and applications running (Prime95, Super Pi, etc). The rail should remain within 12.00VDC +/-0.25. A high-efficiency PSU will also run COOL n QUIET. Note the fan rpm at full load. If it is under 1200 rpm? It is quiet? Put you hand on the PSU's case. Is it cold or luke-warm? Is the exhaust air temperature luke-warm at full load? If "yes" to all those questions, then you probably have a high-efficiency PSU will very good power regulation.

 

[Luckyboy1]

Let's see, by those numbers we are talking about 18-230 watts for all the power needed for the entire rig or just the mommaboard, CPU and system RAM?

 

[Bobthelost]

The entire system will probably draw less than 230W from the wall at max load. Unless you're talking about one with X1800/X1900/7900GTX graphics that is. Then it might get higher.

http://www.silentpcreview.com/article265-page4.html

220W with a 6800GT and a Pentium D was the highest they managed. The 6800GT was fairly power hungry, although not as bad as the newer ATI generations.