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 Aug 25, 2010, 12:27 AM #1 newtekie1 Semi-Retired Folder     Join Date: Nov 2005 Location: Indiana Posts: 17,748 (6.48/day) Thanks: 780 Thanked 5,115 Times in 3,706 Posts System Specs How does PSU efficiency affect me and do I really need an 80 Plus Gold Power Supply? First an explanation of what exactly the efficiency of a PSU means. The efficiency rating on a PSU is simply a rating for how well the PSU converts the AC power it recieves from the outlet to DC power the components of the PC can use. So, for simplicy sake, lets say your PC components are drawing 100w of power. If you have a PSU that is 80% efficient, it will really draw 125w from the AC outlet. I've seen people say that you take the Wattage rating of the PSU, and the efficiency is how much power the PSU can really output for your component. That means that a 500w PSU, rated for 80% efficiency will only be able to supply 400w. This is wrong. A 500w PSU should be able to output 500w to your PC components in one form or another. Efficiency has nothing to do with this. Well if I have a PSU that is rated for 80% efficiency, where does the other 20% go? Simple answer: Heat. Any electricity not converted from AC to DC is given off as heat. Will there ever be 100% efficient Power Supplies? I'm one that lives by the moto "nothing is impossible", so I'm not going to say flat out no. However, I will say that it is highly highly unlikely, and none of use will probably see it in our lifetimes or our childrens lifetimes. If I have a 500w PSU, does that mean it will always draw 500w of power? No. The amount of power drawn is determined by the components of the computer and how much they require. The amount of power drawn will only be equal to what is needed, and no more. If all the components of a computer require 300w to run, then the "load" on the PSU will be 300w and hence the power draw of the PC will always be 300w+Inefficiency no matter if it is a 500w PSU or a 1000w. So what do the different 80 Plus ratings mean? The basic 80 Plus rating means that the PSU is rated for at least 80% efficiency at 20% load, 50% load, and 100% load. The 80 Plus Bronze rating means that the PSU is rated for at least 82% efficiency at 20% load, 85% at 50% load, and 82% at 100% load. The 80 Plus Silver rating means that the PSU is rated for at least 85% efficiency at 20% load, 88% at 50% load, and 85% at 100% load. The 80 Plus Gold rating meas that the PSU is rated for at least 87% efficiency at 20% load, 90% at 50% load, and 87% at 100% load. The 80 Plus Platinum(bet you didn't know there was a Platinum) rating means that the PSU is rated for at least 90% efficiency at 20% load, 92% at 50% load, and 89% at 100% load. Now, that doesn't mean that the PSUs perform exactly at those numbers, but they are close enough, and of course you probably aren't going to use exactly 50% load or whatever, but it is close enough to give a good idea of what a PSU is capable of. What is in it for me? Ah, good question! I made some quick charts to show how much you save in a year over a standard 80% efficient 80 Plus PSU by going with an 80 Plus Bronze/Silver/Gold/Platinum: Some information about these charts. This assumes a 12 Cent/KwH energy rate, if you pay more for your electricity, then the numbers will be slightly higher. This also assumes the computer is running an average of 10 hours per day, again if your computer is on longer, then your savings will be greater. Also remember, "load" in that chart is the percentage load of the capability of the PSU. So 20% load on the 500w PSU would be 100w, that is actually a pretty good area for where a computer would idle. Now of course the other benefit, as I kind of hinted at earlier, is heat. The PSU will put out less heat. Now how much less heat will a Gold PSU output over a Bronze? Well probably not a whole lot, certainly not enough to worry about since it is being expelled right out the back anyway. However, I made a few more charts to show exactly how much less heat will be output by the different rated power supplies compared to an 80 Plus PSU. So with an 800w PSU, even at full load, you are looking at about 100w of heat. That might seem like a lot, but to put it in perspective, space heaters generally start at 500w and go up from there. A 500w space heater will warm a 10' x 10' room up about 10°F, so the extra 100w from the inefficiency might make the room temp rise 2°F. Of course that heat also builds up in the PSU, as a hot PSU looses efficiency. However, that comes down to the cooling system in the PSU, and how effective it is. What if I'm upgrading from a non-80 Plus Power Supply, what are my savings? Ah, another good question, and another few charts. This first chart is how much money you will save over a year. Again, the same rules as above apply, 12 Cents per Kwh, 10 hours per day running. This chart also assumes that your current PSU is 70% efficient at 20% and 100% load, and 75% efficient at 50% load. Without measuring the exact amount, it is impossible to know what efficienty your current PSU is really running at, but these number are pretty good guesses for a non-80 Plus PSU. Now what about the heat savings? Well, here is another chart. Conclusion: Is a 80 Plus Gold PSU necessary? Well, I'm not going to answer that for you, that is up to you to decide. Look at the savings over a year, and make the decision. How many years are you going to be using this PSU? Will it make up for the price difference? You have to answer all this before deciding if a 80 Plus gold PSU is right for you, or if a cheaper 80 Plus Bronze is the way to go. I can say, personally, I'd be fine with an 80 Plus Bronze Power Supply and the only way I'd go with an 80 Plus Gold would be if the prices was very close. Of course an 80 Plus Gold PSU would probably be a great savings for anyone building dedicated Folding or Crunching machines. __________________ Rig1: System Specs. Rig2: A8-5600K@4.4GHz / AsRock FM2A75 Pro4 / 8GB Corsair DDR3-1600 9-9-9-24 / HD7560D / Samsung DVD-Burner / 1.5TB WD Green + 3x3TB WD RED in RAID5 Rig3: Athlon X2 4200+ / M4A79 Deluxe / 4GB G.Skill Pi DDR2-800 4-4-4-12 / GT430 / Sony DVD-Burner / 500GB WD Rig4: Phenom II x6 1605T @ 3.6GHz / Asus M5A99X Evo / 8GB PNY DDR3-1600 9-9-9 / GTX470 & GTX470 / Samsung DVD-Burner / 1.5TB Seagate Last edited by newtekie1; Aug 25, 2010 at 06:01 PM.
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 Aug 25, 2010, 12:33 AM #2 t_ski Staff     Join Date: Apr 2006 Location: Illinois, USA Posts: 8,841 (3.40/day) Thanks: 3,001 Thanked 3,306 Times in 2,528 Posts System Specs Good read __________________ t_ski's stuff for sale ~ TPU Eyefinity Club ~ Heatware Silverstone TJ07 build ~ Mini ITX Home Server build Intel i7 3930K ~ Asus P9X79 Pro ~ 4 x 8GB Corsair Dominator Platinum 1866 C9 ~ Triple 7970's with EK FC-7970 CSQ ~ Triple Asus VW246H LCD's ~ 2 x 120 GB Corsair Force 3 (Raid 0) ~ 500GB WD ~ Lite-On BluRay ~ Nickel-plated Heatkiller 3.0 CU ~ D5 with EK X-top ~ BIX Quad Rad ~ Corsair AX1200 ~ Silverstone TJ07
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 Aug 25, 2010, 12:44 AM #3 AsRock TPU addict   Join Date: Jun 2007 Location: US\ Uk Born Posts: 8,794 (4.07/day) Thanks: 1,675 Thanked 1,348 Times in 1,170 Posts System Specs Sweet, just the reason i got mine as my usage is around 200w - 350w 350w being the best efficiency for my PSU. I got my details from [H] some time ago. Nice read.
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 Aug 25, 2010, 12:49 AM #4 enaher     Join Date: Feb 2009 Posts: 380 (0.25/day) Thanks: 125 Thanked 85 Times in 73 Posts System Specs really nice, to know
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 Aug 25, 2010, 01:50 AM #5 a_ump     Join Date: Nov 2007 Location: Fairmont, WV Posts: 3,081 (1.53/day) Thanks: 450 Thanked 317 Times in 294 Posts System Specs very nice read. i too have heard many people think the efficiency is what it can actually output and i always have to tell them they're wrong lol. Nice for new people to read as well, should be stickied. __________________ My Heatware “MRCL:What if Jesus came by and Apocalypse actually would happen? Weer:Then I'd be more afraid that other works of fiction would come true, such as Harry Potter.”
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 Aug 25, 2010, 01:53 AM #6 theonedub habe fidem     Join Date: Apr 2009 Location: Northern CA Posts: 6,603 (4.45/day) Thanks: 2,269 Thanked 3,188 Times in 1,923 Posts System Specs ^ Seriously, the amount of people that think that astounds me __________________
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 Aug 25, 2010, 02:11 AM #7 assaulter_99     Join Date: Dec 2009 Posts: 1,634 (1.29/day) Thanks: 53 Thanked 284 Times in 266 Posts System Specs Seems we have a guru for everything on tpu, games, headsets, psu's, gpus! Jeez! Thats why I love to stick around so much! Great read btw, hope it helps clearing some peoples mind. __________________ "I assault bases, not women!" : @ssaulter_99
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 Aug 25, 2010, 02:17 AM #8 Mussels Doctor Moderator     Join Date: Oct 2004 Location: Bendigo, Australia (NOT THE USA) Posts: 34,554 (10.97/day) Thanks: 3,699 Thanked 8,691 Times in 6,390 Posts System Specs i got a bit excited with all that tech talk, and now the thread is all stickied. __________________ Edumacational thread about PC Audio My external HDD's.5x samsung 1TB + 2x Seagate 1.5TB = 8 TB external storage 32 Bit OS vs 64 bit OS information How to get hardware accelerated H264 playback (DXVA) Netbook Owners United!
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Aug 25, 2010, 02:19 AM   #9
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 Originally Posted by Mussels i got a bit excited with all that tech talk, and now the thread is all stickied.
I saw what you did there, man behave yourself!
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 Aug 25, 2010, 02:54 AM #10 KieranD Eligible for custom title     Join Date: Aug 2007 Location: Glasgow, Scotland Posts: 5,460 (2.59/day) Thanks: 1,640 Thanked 821 Times in 712 Posts System Specs The transformers aren't 100% efficient is because there is energy loss, some of it is lost to heat ect. That's why there probably wont be 100% efficient because some it is always lost; unless they invent some new transformer or something else to do the job of a transformer. Power grid transformers are 98% and above efficient, Experimental transformers using superconducting windings achieve efficiencies of 99.85% even such a small increase saves a lot of money. EDIT: Efficiency is just that the computer needs like 250w for example but it will draw more than that because they lose energy. A pc needing 250w will use about 294w at 85% efficiency. It needs the extra because if it just drew just 250w from a wall it wouldn't be able to supply 250w when its converted by the transformer. It loses about 46w at 85% efficiency. So it needs to draw more power to make up the lost energy. __________________ http://myinstants.com/instant/transformer/ Last edited by KieranD; Aug 25, 2010 at 03:06 AM.
 Aug 25, 2010, 02:55 AM #11 newtekie1 Semi-Retired Folder     Join Date: Nov 2005 Location: Indiana Posts: 17,748 (6.48/day) Thanks: 780 Thanked 5,115 Times in 3,706 Posts System Specs Thanks guys, glad everyone likes it. Thanks Mussels for stickying it...gross... I think I'm going to add a few different usage senerios to make up a few different charts to add to the one I've got. What power supply ratings does everyone thing I should use? I was thinking adding a chart for 1000w, 650w, 500w? Also adding a chart for 12 and 24 hours usage per day? Oh well, I'll do that tomorrow, I posted that just before leaving work, and I just made it home...I love commuting... __________________ Rig1: System Specs. Rig2: A8-5600K@4.4GHz / AsRock FM2A75 Pro4 / 8GB Corsair DDR3-1600 9-9-9-24 / HD7560D / Samsung DVD-Burner / 1.5TB WD Green + 3x3TB WD RED in RAID5 Rig3: Athlon X2 4200+ / M4A79 Deluxe / 4GB G.Skill Pi DDR2-800 4-4-4-12 / GT430 / Sony DVD-Burner / 500GB WD Rig4: Phenom II x6 1605T @ 3.6GHz / Asus M5A99X Evo / 8GB PNY DDR3-1600 9-9-9 / GTX470 & GTX470 / Samsung DVD-Burner / 1.5TB Seagate
Aug 25, 2010, 02:56 AM   #12
Mussels
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 Originally Posted by newtekie1 Thanks guys, glad everyone likes it. Thanks Mussels for stickying it...gross... I think I'm going to add a few different usage senerios to make up a few different charts to add to the one I've got. What power supply ratings does everyone thing I should use? I was thinking adding a chart for 1000w, 650w, 500w? Also adding a chart for 12 and 24 hours usage per day? Oh well, I'll do that tomorrow, I posted that just before leaving work, and I just made it home...I love commuting...
take your time, and make segments. cover all the basics of PSU's - for example, i still run into people who think a 500W PSU draws 500W all the time. I'd suggest clarifying a little bit more about upgrading PSU's as well, you dont mention older PSU's for comparison - a cheap passive PFC model vs an 80+ gold, would save a toooon of power, for example.

 Aug 25, 2010, 03:12 AM #13 KieranD Eligible for custom title     Join Date: Aug 2007 Location: Glasgow, Scotland Posts: 5,460 (2.59/day) Thanks: 1,640 Thanked 821 Times in 712 Posts System Specs Its actually using more than 500w to convert 500w. Thats just like the max it can convert factoring in loss. So again its like 500w is drawing more power to make up for the loss it has? EDIT: So the more efficient a PSU is the less extra it has to draw from a wall. __________________ http://myinstants.com/instant/transformer/
Aug 25, 2010, 03:21 AM   #14
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Quote:
 Originally Posted by newtekie1 Thanks guys, glad everyone likes it. Thanks Mussels for stickying it...gross... I think I'm going to add a few different usage senerios to make up a few different charts to add to the one I've got. What power supply ratings does everyone thing I should use? I was thinking adding a chart for 1000w, 650w, 500w? Also adding a chart for 12 and 24 hours usage per day? Oh well, I'll do that tomorrow, I posted that just before leaving work, and I just made it home...I love commuting...

go for 400W, 500W and 800W. that covers the actual consumption of every system out there.

stick with 10 hours only for the chart, because its very easy for people to math it to their situation from there - EG, * 2.4 to go from 10 hours to 24 hours

 Aug 25, 2010, 03:22 AM #15 Faith[ROG].Anarchy     Join Date: Aug 2010 Location: Hà Nội, Viet Nam Posts: 415 (0.41/day) Thanks: 80 Thanked 43 Times in 37 Posts System Specs One of the toughest question I've ever faced in my PC life. And now here's the answer. Thanks TPU
 Aug 25, 2010, 03:26 AM #16 JATownes     Join Date: Nov 2008 Location: West Texas Posts: 1,666 (1.01/day) Thanks: 659 Thanked 407 Times in 332 Posts System Specs Great read. Thanks Newtekie. I am sure I will point to this thread more than once when trying to explain PSU efficiency to n00bs. Thanks again. __________________ Please rate my M1dn1ght Rig "I will only buy this if it make's me a sandwich and plays with my balls" - alexsubri Sig compliments of Stefanels
 Aug 25, 2010, 03:29 AM #17 Mussels Doctor Moderator     Join Date: Oct 2004 Location: Bendigo, Australia (NOT THE USA) Posts: 34,554 (10.97/day) Thanks: 3,699 Thanked 8,691 Times in 6,390 Posts System Specs another note, make sure you emphasise on the heat. as PSU's got hotter the efficiency goes down, making them get hotter again... its a vicious cycle that screws you over in summer :P a more efficient PSU heats up less, thus staying more efficient. __________________ Edumacational thread about PC Audio My external HDD's.5x samsung 1TB + 2x Seagate 1.5TB = 8 TB external storage 32 Bit OS vs 64 bit OS information How to get hardware accelerated H264 playback (DXVA) Netbook Owners United!
 Aug 25, 2010, 07:53 AM #18 a_ump     Join Date: Nov 2007 Location: Fairmont, WV Posts: 3,081 (1.53/day) Thanks: 450 Thanked 317 Times in 294 Posts System Specs could you just set up graph so that it simply goes every 100 watts or so? i think it'd just look nicer with more info and be easier to grasp. like i'm thinking 500-1000 with 100watt intervals on bottom of graph. N then you'd have like 4 different colored lines for the different 80% ratings. With the left side covering the extra wattage you draw from an outlet. Like if i got it correctly. 500watts at 80% efficiency will actually draw ~600watts due to the efficiency at converting dc to ac? That's my understanding and im just now starting to get into PSU's lol __________________ My Heatware “MRCL:What if Jesus came by and Apocalypse actually would happen? Weer:Then I'd be more afraid that other works of fiction would come true, such as Harry Potter.”
Aug 25, 2010, 08:00 AM   #19
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 Originally Posted by a_ump could you just set up graph so that it simply goes every 100 watts or so? i think it'd just look nicer with more info and be easier to grasp. like i'm thinking 500-1000 with 100watt intervals on bottom of graph. N then you'd have like 4 different colored lines for the different 80% ratings. With the left side covering the extra wattage you draw from an outlet. Like if i got it correctly. 500watts at 80% efficiency will actually draw ~600watts due to the efficiency at converting dc to ac? That's my understanding and im just now starting to get into PSU's lol
you're on the right track.

in order for an 80% efficient PSU (lets assume its actually 80% efficient, for this) to deliver 500W of power to your system (which is a very high figure, unless you're running 2 or more video cards) would draw 600W at the wall.

that 100W extra would end up being heat output inside the PSU - so in that example, going from an 80% PSU to a 90% one, would save you 50W of power - as well as 50W of heat.

also keep in mind the easy comparison to an electric heater. i've got a small one here that goes from 1000W to 2000W - you could say that saving 100W of heat output from your PC, is saving you 1/10th the heat the heater would have made (or alternately, for every ten hours your PC is on, its the same as having that heater on for one hour)

when you think of how hot a room can get from having a heater (even on low) for an hour, you start to realise just how much these heat and power savings can really add up.

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 Aug 25, 2010, 08:27 AM #20 a_ump     Join Date: Nov 2007 Location: Fairmont, WV Posts: 3,081 (1.53/day) Thanks: 450 Thanked 317 Times in 294 Posts System Specs yea i forgot bout the thermal part of it aswell __________________ My Heatware “MRCL:What if Jesus came by and Apocalypse actually would happen? Weer:Then I'd be more afraid that other works of fiction would come true, such as Harry Potter.”
Aug 25, 2010, 08:29 AM   #21
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 Originally Posted by Faith[ROG].Anarchy One of the toughest question I've ever faced in my PC life. And now here's the answer. Thanks TPU
Questions where asking could save you a bit of pain:

Question 1 : "What PSU do I need?"
Question 2: "Which hole does it go in?"
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 Aug 25, 2010, 09:02 AM #22 Tatty_One Senior(Citizen)Moderator     Join Date: Jan 2006 Location: Worcestershire, UK Posts: 12,741 (4.75/day) Thanks: 1,093 Thanked 1,934 Times in 1,436 Posts System Specs Very nice read thank you, well written, concise and to the point.... just how I like them! I see a potential reviewer for TPU here __________________
 Aug 25, 2010, 09:26 AM #23 a_ump     Join Date: Nov 2007 Location: Fairmont, WV Posts: 3,081 (1.53/day) Thanks: 450 Thanked 317 Times in 294 Posts System Specs as much as newtekie contradicts by being specific on things in an argument i'm surprised he hasn't already tried to be a reviewer just to prove all his points haha __________________ My Heatware “MRCL:What if Jesus came by and Apocalypse actually would happen? Weer:Then I'd be more afraid that other works of fiction would come true, such as Harry Potter.”
Aug 25, 2010, 09:29 AM   #24
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 Originally Posted by a_ump as much as newtekie contradicts by being specific on things in an argument i'm surprised he hasn't already tried to be a reviewer just to prove all his points haha
TPU reviewers are veeeery heavily screened - i applied and didnt make it in, and i used to be a reviewer at 3DChipset.

 Aug 25, 2010, 10:16 AM #25 a_ump     Join Date: Nov 2007 Location: Fairmont, WV Posts: 3,081 (1.53/day) Thanks: 450 Thanked 317 Times in 294 Posts System Specs mussels weren't big enough XD. yea i noticed there's only a handful of people that do em. OT: sorta lol, have we created a thread section that's just strait up full of informative threads like this? if not we should, just like a thread section not postable unless a thread is moved by a mod for its informative status. __________________ My Heatware “MRCL:What if Jesus came by and Apocalypse actually would happen? Weer:Then I'd be more afraid that other works of fiction would come true, such as Harry Potter.”
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