Overclock.net › Forums › Components › Power Supplies › Power Supply Questions
New Posts  All Forums:Forum Nav:

Power Supply Questions

post #1 of 6
Thread Starter 
Well, as the title clearly says, I have a couple questions about power supply units. I've been reading a tutorial on PSUs from hardwaresecrets.com, which has been immensely helpful, but it leaves me with these confusions... 1) According to the article, PSUs reach their maximum efficiency when running at 220 V; why is this? Also, if your PSU uses voltage auto-select, is it safe to assume that it will run at this optimum 220 V, or could it get stuck at a lower voltage like 110 V? 2) I have a fairly outdated PSU; its total power max is 250 W, and it has a manual switch for using 115 V or 230 V input. Next to Input on the label, it reads "100-120V~6A , 200-240V~3A 50/60Hz." Can this PSU only reach its maximum 250W power when using 230 V input? Moreover, does this mean that my efficiency is only 250W / (230V x 3A) = 36% at best?

Thanks in advance for your assistance!
post #2 of 6
Quote:
Originally Posted by Shundra9 View Post

Well, as the title clearly says, I have a couple questions about power supply units. I've been reading a tutorial on PSUs from hardwaresecrets.com, which has been immensely helpful, but it leaves me with these confusions... 1) According to the article, PSUs reach their maximum efficiency when running at 220 V; why is this?

I don't know, but PSUs sold in the US advertise the efficiency that you'd get at 110 to 120V.

Quote:
Originally Posted by Shundra9 View Post

Also, if your PSU uses voltage auto-select, is it safe to assume that it will run at this optimum 220 V, or could it get stuck at a lower voltage like 110 V?

It just depends on the voltage your outlet is supplying. Ours here in St. Paul Minnesota supply 120V. If you're not sure what you're getting, then you can use a meter like the Kill A Watt.

Quote:
Originally Posted by Shundra9 View Post

2) I have a fairly outdated PSU; its total power max is 250 W, and it has a manual switch for using 115 V or 230 V input. Next to Input on the label, it reads "100-120V~6A , 200-240V~3A 50/60Hz." Can this PSU only reach its maximum 250W power when using 230 V input? Moreover, does this mean that my efficiency is only 250W / (230V x 3A) = 36% at best?

Thanks in advance for your assistance!

No, efficiency and a PSU's capacity are absolutely unrelated. The PSU will always have the 250W capacity regardless of how low its efficiency is.
It's a computer!
(19 items)
 
  
CPUMotherboardGraphicsRAM
i5-2500K @ 4.5GHz (1.400-1.424V in Manual Mode) 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 
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 
Mouse PadAudioAudio
Basic, but premium round X-Fi Titanium HD Klipsch ProMedia 2.1 (with 16 AWG Monster Cable... 
  hide details  
Reply
It's a computer!
(19 items)
 
  
CPUMotherboardGraphicsRAM
i5-2500K @ 4.5GHz (1.400-1.424V in Manual Mode) 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 
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 
Mouse PadAudioAudio
Basic, but premium round X-Fi Titanium HD Klipsch ProMedia 2.1 (with 16 AWG Monster Cable... 
  hide details  
Reply
post #3 of 6
Transformers have less % losses for higher voltages. PSU's are designed to run at mid-range current so that's where their highest efficiencies are. The 250W maximum applies for all indicated input voltages.
post #4 of 6
And again, a PSU's capacity has nothing to do with its efficiency.
It's a computer!
(19 items)
 
  
CPUMotherboardGraphicsRAM
i5-2500K @ 4.5GHz (1.400-1.424V in Manual Mode) 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 
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 
Mouse PadAudioAudio
Basic, but premium round X-Fi Titanium HD Klipsch ProMedia 2.1 (with 16 AWG Monster Cable... 
  hide details  
Reply
It's a computer!
(19 items)
 
  
CPUMotherboardGraphicsRAM
i5-2500K @ 4.5GHz (1.400-1.424V in Manual Mode) 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 
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 
Mouse PadAudioAudio
Basic, but premium round X-Fi Titanium HD Klipsch ProMedia 2.1 (with 16 AWG Monster Cable... 
  hide details  
Reply
post #5 of 6
Thread Starter 
Ok I know this was already over a week ago, but I feel like my questions still haven't been answered.

I get why the optimum efficiency is achieved around 220V now, but is this the voltage that a PSU with auto-select (and/or active PFC) will always utilize if it can? Obviously it depends on my outlet, and the PSU will pull whatever it has to, but what I'm asking is: when it CAN pull the most efficient 220V, is that what it WILL pull?

Second, a PSU can only hold its maximum labeled power output for certain amount of time, sometimes only a few seconds. What I was asking there was: can a PSU only sustain its maximum possible output on a SPECIFIC input voltage, like 220V, or can it reach this power on any voltage, albeit with weaker current?" Your previous responses lead me to believe that the latter is correct, but I just wanted to be sure.
post #6 of 6
Quote:
Originally Posted by Shundra9 View Post

Ok I know this was already over a week ago, but I feel like my questions still haven't been answered.

I get why the optimum efficiency is achieved around 220V now, but is this the voltage that a PSU with auto-select (and/or active PFC) will always utilize if it can? Obviously it depends on my outlet, and the PSU will pull whatever it has to, but what I'm asking is: when it CAN pull the most efficient 220V, is that what it WILL pull?

It just adjusts to the voltage being supplied by the outlet. It's truly just as simple as that.

Quote:
Originally Posted by Shundra9 View Post

Second, a PSU can only hold its maximum labeled power output for certain amount of time, sometimes only a few seconds. What I was asking there was: can a PSU only sustain its maximum possible output on a SPECIFIC input voltage, like 220V, or can it reach this power on any voltage, albeit with weaker current?" Your previous responses lead me to believe that the latter is correct, but I just wanted to be sure.

On any voltage because the efficiency has absolutely nothing to do with a PSU's capacity. The only thing the efficiency affects is how much power it has to pull from the wall outlet in order to create the power that the computer is pulling from it. The higher the input voltage, the more efficient it is and thus the less power it has to pull from the wall outlet in order to create that same wattage. So if you had a knob on your wall outlet that enabled you to gradually adjust your outlet's voltage all the way from 110V to 220V while your computer is pulling 500W, then you wouldn't be affecting the amount of power being delivered to your computer nor would you be affecting your PSU's capacity. All you would be affecting is how much power the PSU has to pull from the outlet in order to deliver that 500W. The closer and closer you get to 220V, the lower and lower the amount of power the PSU has to pull from the wall outlet in order to deliver that 500W which means it's becoming more and more efficient.

Furthermore, you're talking about peak-rated PSUs here and therefore you're talking about PSUs that are generally never good to recommend or buy. A good quality-made PSU will be a continuous-rated unit meaning that it's supposed to be able to deliver its rated wattage 24/7 if it's ever needed. There's more to it than that, but still. A peak-rated unit is one like you described: it can only deliver its rated wattage for a very brief amount of time.

I"m very glad you asked because I feel like we nailed it here! smile.gif Sometimes it takes a couple of tries. hehe
It's a computer!
(19 items)
 
  
CPUMotherboardGraphicsRAM
i5-2500K @ 4.5GHz (1.400-1.424V in Manual Mode) 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 
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 
Mouse PadAudioAudio
Basic, but premium round X-Fi Titanium HD Klipsch ProMedia 2.1 (with 16 AWG Monster Cable... 
  hide details  
Reply
It's a computer!
(19 items)
 
  
CPUMotherboardGraphicsRAM
i5-2500K @ 4.5GHz (1.400-1.424V in Manual Mode) 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 
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 
Mouse PadAudioAudio
Basic, but premium round X-Fi Titanium HD Klipsch ProMedia 2.1 (with 16 AWG Monster Cable... 
  hide details  
Reply
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Power Supplies
Overclock.net › Forums › Components › Power Supplies › Power Supply Questions