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01-31-2012
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#1 | | Windows 7 Home premium 64bit SP 1 |
Total Amps Could someone please help me out here?
Listed are the specs for my Athena AP-MFATX35P8 350W Flex ATX Power Supply.
Output
Voltage +5V -5V +12V1 +12V2 -12V +3.3V +5V-SB
Current 15A 0.5A 11A 11A 0.8A 15A 3.0A
What I don't understand here is +12V1 (11A) and +12V2 (11A)?
I asume each one is called or designated as a "12V Rail"?
If so which on powers the video card? or would one add both of these +12V values together and use a total?
Thanks
N2
| My System Specs | | System Manufacturer/Model Number Gateway GT 5676 OS Windows 7 Home premium 64bit SP 1 CPU AMD Phenom Quad Core 9600 2.3 GHz Motherboard 4006272R - Foxconn (Bengal) RS780 Motherboard Memory 8GB of DDR2 Graphics Card Integrated ATI Radeon HD 3200 video /Sapphire Radeon HD 3470 Sound Card Integrated ALC888S HD codec 7.1 Monitor(s) Displays 19" Samsung SyncMaster Screen Resolution 1440x900 Keyboard HP Mouse Logitech Laser PSU Ultra LSP 650W Case Gateway 5-Bay uATX Computer Case (Carbon Fiber) Cooling CPU - Arctic Cooler Freezer 64 Hard Drives Two On board 320 GB 7200 RPM SATA II hard drives (640 GB drive space)
One Toshiba 1TB External
One WD 300GB External
One WD 15GB Removable HD Internet Speed Down 14.48Mbps Up 1.88Mbps Bresnan (Optimum) |
01-31-2012
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#2 | | Windows 7 SP1, Home Premium, 64-bit |
I think you would use the total---11 plus 11 gives 22 amps total on the 12 volt rail.
You could go over to jonnyguru.com and maybe read some tutorials. Or silentpcreview.com.
If I remember correctly, many PSUs that appear to have 2 12 volt rails, such as yours, in reality only have 1. The apparent "split" is somewhat of an illusion--but I don't recall the details. | My System Specs | | System Manufacturer/Model Number Ignatz Special; 4 speed manual gearbox; factory air conditioning; one of one OS Windows 7 SP1, Home Premium, 64-bit CPU Intel Sandy Bridge i5-2500, not overclocked Motherboard Gigabyte H67A-UD3H-B3, full ATX Memory 4 GB Crucial DDR3-1333 Graphics Card none; graphics are integrated on CPU Sound Card onboard: Realtek ALC892; external: USB Behringer UF0-202 Monitor(s) Displays NEC 90GX2-BK 19" LCD Screen Resolution 800 x 640 Keyboard Leopold Tenkeyless with Cherry Blue switches, USB Mouse Logitech or Microsoft optical wired; either USB or PS 2 PSU Seasonic SS-560KM, modular Case Antec Solo II Cooling CPU: Scythe Big Shuriken; Case: Scythe Slipstream 800 & 500 Hard Drives System: Intel 320 Series SSD, 80 GB;
Data: Samsung Spinpoint 103SJ, 1 TB;
Backup: WD Caviar Green WD15EADS-00P8B0, 1.5TB Other Info Power consumption of this system, including monitor: 68 watts at idle; 144 watts at full load |
01-31-2012
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#3 | | Windows 7 Home premium 64bit SP 1 |
Thanks ignatzatsonic, jonnyguru.com states the following, so I would tend to agree with you.
N2 - Power Supplies With Multiple +12V Rails
- Is it true that some PSU's that claim to be multiple +12V rails don't have the +12V rail split at all?
- Yes, this is true. But it's the exception and not the norm. The power supply's label may reflect a +12V rail that is split into two, three or four, when in reality there is no additional components in place to limit how much current can be delivered to a connector.
Last edited by N2Abyss; 01-31-2012 at 03:31 PM..
Reason: mistype
| My System Specs | | System Manufacturer/Model Number Gateway GT 5676 OS Windows 7 Home premium 64bit SP 1 CPU AMD Phenom Quad Core 9600 2.3 GHz Motherboard 4006272R - Foxconn (Bengal) RS780 Motherboard Memory 8GB of DDR2 Graphics Card Integrated ATI Radeon HD 3200 video /Sapphire Radeon HD 3470 Sound Card Integrated ALC888S HD codec 7.1 Monitor(s) Displays 19" Samsung SyncMaster Screen Resolution 1440x900 Keyboard HP Mouse Logitech Laser PSU Ultra LSP 650W Case Gateway 5-Bay uATX Computer Case (Carbon Fiber) Cooling CPU - Arctic Cooler Freezer 64 Hard Drives Two On board 320 GB 7200 RPM SATA II hard drives (640 GB drive space)
One Toshiba 1TB External
One WD 300GB External
One WD 15GB Removable HD Internet Speed Down 14.48Mbps Up 1.88Mbps Bresnan (Optimum) |
01-31-2012
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#4 | | Windows 7 64 Bit Home Premium SP1 |
Good post. It sent me on a search to confirm and I found this. Interesting. Multiple +12 V rails
As power supply capacity increased, the ATX power supply standard was amended (beginning with version 2.0 [2]) to include: 3.2.4. Power Limit / Hazardous Energy Levels Under normal or overload conditions, no output shall continuously provide more than 240
VA under any conditions of load including output short circuit, per the requirement of UL 1950/CSA 950/EN 60950/IEC 950.
—ATX12V Power Supply Design Guide, version 2.2[3] This is a safety limit on the amount of power that may pass, in case of a fault, through any one wire. That much power can significantly overheat a wire, and would be more likely to melt the insulation and possibly start a fire. Each wire must be current-limited to no more than 20 A; typical supplies guarantee 18 A without triggering the current limit. Power supplies capable of delivering more than 18 A at 12 V connect wires in groups to two or more current sensors which will shut down the supply if excess current flows. Unlike a fuse or circuit breaker, these limits reset as soon as the overload is removed.
Ideally, there would be one current limit per wire, but that would be prohibitively expensive. Since the limit is far larger than the reasonable current draw through a single wire, manufacturers typically group several wires together and apply the current limit to the entire group. Obviously, if the group is limited to 240 VA, so is each wire in it. Typically, a power supply will guarantee at least 17 A at 12 V by having a current limit of 18.5 A, plus or minus 8%. Thus, it is guaranteed to supply at least 17 A, and guaranteed to cut off before 20 A.
These groups are the so-called "multiple power supply rails". They are not fully independent; they are all connected to a single high-current 12 V source inside the power supply, but have separate current limit circuitry. The current limit groups are documented so the user can avoid placing too many high-current loads in the same group. Originally, a power supply featuring "multiple +12 V rails" implied one able to deliver more than 20 A of +12 V power, and was seen as a good thing. However, people found the need to balance loads across many +12 V rails inconvenient. This problem was exacerbated by the fact that the assignment of connectors to rails is done at manufacturing time, and it is not always possible to move a given load to a different rail.
Rather than add more current limit circuits, many manufacturers have chosen to ignore the requirement and increase the current limits above 20 A per rail, or provide "single-rail" power supplies that omit the current limit circuitry. (In some cases, in violation of their own advertising claims to include it. For one example of many, see [4]) The requirement was deleted from version 2.3 (March 2007) of the ATX12V power supply specifications. [5]
Because of the above standards, almost all high-power supplies claim to implement separate rails, however this claim is often false; many omit the necessary current-limit circuitry, [6] both for cost reasons and because it is an irritation to customers. [7] (The lack is sometimes advertised as a feature under names like "rail fusion" or "current sharing".)
More along the same lines here: Maximum PC | Single-rail versus multi-rail power supplies | My System Specs | | System Manufacturer/Model Number DESKTOP - Home Built - March 2009 OS Windows 7 64 Bit Home Premium SP1 CPU i7-920 Motherboard Asus P6T - Bios 1408 Memory Corsair TR3X6G1333C9 - 6GB Graphics Card EVGA GeForce GTX260+ - Driver 296.10 Sound Card On board Realtek ACL1200 Monitor(s) Displays Dell 2007FP Screen Resolution 1280 x 960 Keyboard MS KC-0405 Mouse Intellimouse 5-button PSU Corsair CMPSU-750TX - 750 watt Case Lian Li PC-K10B Cooling Standard, 3 120mm case fans Hard Drives #1- Western Digital WD6401AALS Sata Black
#2- Western Digital WD6401AALS Sata Black Internet Speed 20Mbits/Sec (on a good day) |
01-31-2012
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#5 | | |

Quote: Originally Posted by N2Abyss Could someone please help me out here?
Listed are the specs for my Athena AP-MFATX35P8 350W Flex ATX Power Supply.
Output
Voltage +5V -5V +12V1 +12V2 -12V +3.3V +5V-SB
Current 15A 0.5A 11A 11A 0.8A 15A 3.0A
What I don't understand here is +12V1 (11A) and +12V2 (11A)?
I asume each one is called or designated as a "12V Rail"?
If so which on powers the video card? or would one add both of these +12V values together and use a total?
Thanks
N2 The video card will be hooked up to only one of those rails via PCI unless you have an auxiliary PCI-E power connector on the card and from the PSU. So 11A is it mate. | My System Specs | | System Manufacturer/Model Number Home built (GeneO industries)/Model 2 OS Windows 7 64 bit SP1 CPU i5 2500k @ 4.5 GHz, 1.256V 120 GFlop (with AVX) Motherboard ASUS P8Z68-V PRO/GEN3 Memory 16GB (4GBx4) 1600MHz G.skill Ripjaws X 8-8-8-24 Graphics Card Asus Nvidia ENGTS450, 1GB 4030 MHz DDR5 clock, 915 Mhz GPU Sound Card Onboard Realtek HD Monitor(s) Displays NEC Spectraview 2490WUXi-SV Screen Resolution 1920 x 1200 Keyboard HP Wireless Mouse HP wireless PSU Antec TruePower New 650W Case Fractal Design "Define R3" Cooling CM Hyper 212+ push/pull, 5 120mm, 1 140mm case fans Hard Drives Crucial 128GB M4 (system), 2x WD Caviar 1TB Black internal (data), 1x Seagate 750G Barracuda Internal (backups), 1x WD Blue 6Gb/s 320GB Internal, 1x Corsair F40 SSD for cache, 1x 2TB eSata WD20EARS Green, 2x 500GB Seagate external USB, 1x 350GB exte Internet Speed 25.7 Mb/s down, 4.5 Mb/s up Other Info USB 3.0 x4 , SATA III x4, eSATA x3, SATA II x4, USB 2.0 x8. 2 Samsung DVD R/W drives.
WEI: CPU 7.7, Memory 7.9, Graphics 7.4, Disk 7.9 |
01-31-2012
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#6 | | |

Quote: Originally Posted by N2Abyss Thanks ignatzatsonic, jonnyguru.com states the following, so I would tend to agree with you.
N2 - Power Supplies With Multiple +12V Rails
- Is it true that some PSU's that claim to be multiple +12V rails don't have the +12V rail split at all?
- Yes, this is true. But it's the exception and not the norm. The power supply's label may reflect a +12V rail that is split into two, three or four, when in reality there is no additional components in place to limit how much current can be delivered to a connector.
No I don't think this is true. If a current model power supply has only one +12V rail supplying all of the power, it will say so. Power supply standards used to specify a limit to the current a single rail supplied, so maybe back then some manufacturers may have cheated, but that restriction has long been lifted from the standards.
oop, see TV already explained this, | My System Specs | | System Manufacturer/Model Number Home built (GeneO industries)/Model 2 OS Windows 7 64 bit SP1 CPU i5 2500k @ 4.5 GHz, 1.256V 120 GFlop (with AVX) Motherboard ASUS P8Z68-V PRO/GEN3 Memory 16GB (4GBx4) 1600MHz G.skill Ripjaws X 8-8-8-24 Graphics Card Asus Nvidia ENGTS450, 1GB 4030 MHz DDR5 clock, 915 Mhz GPU Sound Card Onboard Realtek HD Monitor(s) Displays NEC Spectraview 2490WUXi-SV Screen Resolution 1920 x 1200 Keyboard HP Wireless Mouse HP wireless PSU Antec TruePower New 650W Case Fractal Design "Define R3" Cooling CM Hyper 212+ push/pull, 5 120mm, 1 140mm case fans Hard Drives Crucial 128GB M4 (system), 2x WD Caviar 1TB Black internal (data), 1x Seagate 750G Barracuda Internal (backups), 1x WD Blue 6Gb/s 320GB Internal, 1x Corsair F40 SSD for cache, 1x 2TB eSata WD20EARS Green, 2x 500GB Seagate external USB, 1x 350GB exte Internet Speed 25.7 Mb/s down, 4.5 Mb/s up Other Info USB 3.0 x4 , SATA III x4, eSATA x3, SATA II x4, USB 2.0 x8. 2 Samsung DVD R/W drives.
WEI: CPU 7.7, Memory 7.9, Graphics 7.4, Disk 7.9 All times are GMT -5. The time now is 01:25 PM. |  |