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post #11 of 46
Quote:
Originally Posted by TwoCables View Post

No.

On PSU Efficiency

PSU "50% Load" Myth
^^^ With good, modern PSUs they are still about 90% efficient even at full load.
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post #12 of 46
Quote:
Originally Posted by TwoCables View Post

No.

On PSU Efficiency

PSU "50% Load" Myth

Well that seems like an awful averaging of efficiencies lol. Taking arithmetic average for possible load scenarios? Efficiencies should be weighted by the power draw. You should care less about efficiency at idle and more about efficiency at full load. After all, it's your power bill that matters.
post #13 of 46

Damn, you guys are speed readers.  It took me a LOT longer to read both of those articles than it took you guys.  I'm jealous.

 

 

Quote:
Originally Posted by AndyM95 View Post


^^^ With good, modern PSUs they are still about 90% efficient even at full load.

 

I've found that most people want the efficiency that was advertised because most people are basing their purchase on the 80+ Certification (which I recommend not doing, but hey).

 

 

Quote:
Originally Posted by Whalemeal View Post


Well that seems like an awful averaging of efficiencies lol. Taking arithmetic average for possible load scenarios? Efficiencies should be weighted by the power draw. You should care less about efficiency at idle and more about efficiency at full load. After all, it's your power bill that matters.

 

This is about the average power draw.  If your maximum power draw is 500W, then are you going to buy a 1000W PSU just so your maximum power draw is 50% of your PSUs capacity?

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It's a computer!
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post #14 of 46
Quote:
Originally Posted by TwoCables View Post

Damn, you guys are speed readers.  It took me a LOT longer to read both of those articles than it took you guys.  I'm jealous.



I've found that most people want the efficiency that was advertised because most people are basing their purchase on the 80+ Certification (which I recommend not doing, but hey).



This is about the average power draw.  If your maximum power draw is 500W, then are you going to buy a 1000W PSU just so your maximum power draw is 50% of your PSUs capacity?

No. But I would buy a PSU that can run my gaming power draw at 50~60% power. In OP's setup I estimate that will be around 400W+.So I recommend him to get at least 750W+. You should definitely weight more on the scenario where you use your computer most intensively.
post #15 of 46
Quote:
Originally Posted by Whalemeal View Post


No. But I would buy a PSU that can run my gaming power draw at 50~60% power. In OP's setup I estimate that will be around 400W+.So I recommend him to get at least 750W+. You should definitely weight more on the scenario where you use your computer most intensively.

 

Well, if the only thing the computer is used for is gaming from the moment it's turned on to the moment it's turned off, then the average load can be determined mostly by that - but not entirely because there's still e-mail, internet, OCN (lol yeah, I separated internet and OCN), etc.  If the computer is left on 24/7 and is idling when it's not in use, then the gaming is nowhere near being the average load.

 

His gaming load will max out at about 500-525W.  Any quality-made 650W power supply would be just fine for this because the kind of PSU he'll end up with is one that can easily deliver 650W continuously if it's ever needed.  I'm not going to recommend anything 'bigger' than that because it's just not needed at all.  Let's say that you need a bucket for exactly 5 gallons because that's the most you'll ever put in it.  Let's say that good 5 gallon buckets can actually hold about 7-8 gallons if you fill them to the very top.  This means you can carry those 5 gallons around without spilling and it also leaves you with lots of room for water displacement.  So, there's no need to get a bucket that has a larger capacity because your quality-made bucket can hold more than 5 gallons so that you can carry it around comfortably without any problems and you can displace water any time you need to without it flowing over the top.

 

I know, that was not the greatest analogy, but it was all I had in my mind for some reason.

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It's a computer!
(19 items)
 
  
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i5-2500K @ 4.5GHz (1.368-1.384V fixed voltage) ASUS P8P67 EVO B3 (UEFI ver. 1850) GTX 780 ASUS DirectCU II (1228 / 6300, 1.180V) G.SKILL Ripjaws X 8GB (2 x 4GB) 1866MHz, CL9 
Hard DriveHard DriveHard DriveOptical Drive
250 GB Samsung 840 EVO (C:\) 250 GB Samsung 840 EVO (D:\) 150 GB WD VelociRaptor Samsung SH-S243N 24x DVD Burner 
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post #16 of 46
Quote:
Originally Posted by TwoCables View Post

Well, if the only thing the computer is used for is gaming from the moment it's turned on to the moment it's turned off, then the average load can be determined mostly by that - but not entirely because there's still e-mail, internet, OCN (lol yeah, I separated internet and OCN), etc.  If the computer is left on 24/7 and is idling when it's not in use, then the gaming is nowhere near being the average load.

His gaming load will max out at about 500-525W.  Any quality-made 650W power supply would be just fine for this because the kind of PSU he'll end up with is one that can easily deliver 650W continuously if it's ever needed.  I'm not going to recommend anything 'bigger' than that because it's just not needed at all.  Let's say that you need a bucket for exactly 5 gallons because that's the most you'll ever put in it.  Let's say that good 5 gallon buckets can actually hold about 7-8 gallons if you fill them to the very top.  This means you can carry those 5 gallons around without spilling and it also leaves you with lots of room for water displacement.  So, there's no need to get a bucket that has a larger capacity because your quality-made bucket can hold more than 5 gallons so that you can carry it around comfortably without any problems and you can displace water any time you need to without it flowing over the top.

I know, that was not the greatest analogy, but it was all I had in my mind for some reason.

Well I agree that 650W is cost efficient for hist setup. But the calculation in the article you pointed is just wrong. If you calculate the actual energy that is wasted in air with a given usage scenario, you will find that 650W will give less number albeit not enough to justify the price difference between two PSUs. Even though you turn on your computer 24/7 and play games for like 3 hours, the energy wasted in air is probably more from gaming.
post #17 of 46
Quote:
Originally Posted by Whalemeal View Post


Well I agree that 650W is cost efficient for hist setup. But the calculation in the article you pointed is just wrong. If you calculate the actual energy that is wasted in air with a given usage scenario, you will find that 650W will give less number albeit not enough to justify the price difference between two PSUs. Even though you turn on your computer 24/7 and play games for like 3 hours, the energy wasted in air is probably more from gaming.

 

How is it wrong?  What part is wrong?  I don't know see what's incorrect.  They measured the power draw at the wall outlet with the 7970s maxed out, their CPU was idling, so I added 150W to that.  Then I multiplied that value by .85 for 85% efficiency because their test PSU is about 85% efficient, and so that's the power that the system would be pulling from the PSU in such an extreme situation.  The actual gaming load is lower, at about 500-525W tops.  Then you take a quality-made 650W than can easily deliver 650W non-stop, and these power draws are easy for it.  It would be a complete waste of money to get a 750W PSU unless the 7970s are to be heavily overclocked along with the 3770K.  So, I'm waiting to find out if Dan will be overclocking his 7970s.

It's a computer!
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It's a computer!
(19 items)
 
  
CPUMotherboardGraphicsRAM
i5-2500K @ 4.5GHz (1.368-1.384V fixed voltage) ASUS P8P67 EVO B3 (UEFI ver. 1850) GTX 780 ASUS DirectCU II (1228 / 6300, 1.180V) G.SKILL Ripjaws X 8GB (2 x 4GB) 1866MHz, CL9 
Hard DriveHard DriveHard DriveOptical Drive
250 GB Samsung 840 EVO (C:\) 250 GB Samsung 840 EVO (D:\) 150 GB WD VelociRaptor Samsung SH-S243N 24x DVD Burner 
Optical DriveCoolingOSMonitor
Samsung SH-S203N 20X DVD Burner Thermaltake Frio Win 7 Home Premium x64 SP1 Retail AOC G2460PG (24" 1920 x 1080 144Hz G-SYNC) 
KeyboardPowerCaseMouse
Filco Majestouch 104-key Cherry MX Blues w/NKRO Corsair HX650 (Bronze, ordered on 12-12-2009) CM 690 Intellimouse Optical (1.1A) 1000Hz polling rate 
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Basic, but premium round X-Fi Titanium HD Klipsch ProMedia 2.1 (with 16 AWG Monster Cable... 
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post #18 of 46
Quote:
Originally Posted by TwoCables View Post

How is it wrong?  What part is wrong?  I don't know see what's incorrect.  They measured the power draw at the wall outlet with the 7970s maxed out, their CPU was idling, so I added 150W to that.  Then I multiplied that value by .85 for 85% efficiency because their test PSU is about 85% efficient, and so that's the power that the system would be pulling from the PSU in such an extreme situation.  The actual gaming load is lower, at about 500-525W tops.  Then you take a quality-made 650W than can easily deliver 650W non-stop, and these power draws are easy for it.  It would be a complete waste of money to get a 750W PSU unless the 7970s are to be heavily overclocked along with the 3770K.  So, I'm waiting to find out if Dan will be overclocking his 7970s.

I'm talking about the article titled PSU "50% Load" Myth that talks bout 650W vs 400W. Let me be a math nerd here. Let u(x) be your usage scenario at x Watt of load that integrates to 24 hours. Let e(x) be the efficiency curve of a power supply. Then the average efficiency you should care about is integral of u(x)*x*e(x) over 0 to max draw. However the article says that average efficiency is integral of u(x)*e(x) (well even cruder than that but the spirit is the same).
Edited by Whalemeal - 2/21/13 at 10:17am
post #19 of 46
Thread Starter 
Quote:
Originally Posted by TwoCables View Post

So, I'm waiting to find out if Dan will be overclocking his 7970s.

Hey, sorry, I'm back, I was out to lunch, so many responses! my plan is to game with this obv, but yes I will be overclocking, I am going to get as much out of this as possible, and to touch on my purchasing abilities, yes Newegg is possible, I live in the US. This sounds Like I want an 850, just so I can be happy that I will be ready for the future and because having more makes me happy. So would anyone like to help me on which of the 850's is the best to have? again with using facts and personal experience please:)

(Side note: there are so many different makers/versions of the Radeon HD 7970...does it matter who I go with? also, I am going with a red theme on my case if that helps with decisions)

Two Cables, you are being very helpful, and thank you for that!
post #20 of 46
Ah the mystical 50% load for greatest efficiency Unicorn

A good quality Bronze rated unit wil have a 3% or lower swing in efficiency between 20-100% load
Gold will get you in the 1.5% area

Who thinks it matters ?
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