Overclock.net › Forums › Components › Power Supplies › 12 volt rail question
New Posts  All Forums:Forum Nav:

12 volt rail question

post #1 of 7
Thread Starter 
I have always wondered when you read about a mobo that requires a CPU 4 pin connector do you always use the 4 volt rail from the psu in the specs description. Or when you read about psu specs it will indicate CPU 4 pin?
OverKill
(18 items)
 
  
CPUMotherboardGraphicsGraphics
AMD Phenom II X6 1055T Gigabyte 890FXA ATI FirePro V3800 ATI FirePro V3800 
RAMHard DriveHard DriveOptical Drive
16gb GSkill 10666 Seagate Western Digital  LG Blue Ray 
CoolingOSMonitorMonitor
stock air 7 Pro 64 bit (2)22" Acer x223w (2)23" Acer G235H 
KeyboardPowerCaseMouse
Microsoft Wireless Antec 900watt Antec 300 Wacom Tablet 
Audio
Logitech Speakers and sub 
  hide details  
Reply
OverKill
(18 items)
 
  
CPUMotherboardGraphicsGraphics
AMD Phenom II X6 1055T Gigabyte 890FXA ATI FirePro V3800 ATI FirePro V3800 
RAMHard DriveHard DriveOptical Drive
16gb GSkill 10666 Seagate Western Digital  LG Blue Ray 
CoolingOSMonitorMonitor
stock air 7 Pro 64 bit (2)22" Acer x223w (2)23" Acer G235H 
KeyboardPowerCaseMouse
Microsoft Wireless Antec 900watt Antec 300 Wacom Tablet 
Audio
Logitech Speakers and sub 
  hide details  
Reply
post #2 of 7
Almost all psu's have 4 pin cpu connectors. Some of them also have 8 pin, which is just 2 x 4 pin (lower resistance and ripple, no actual power increase).
The Butthurt Box
(21 items)
 
   
CPUMotherboardGraphicsGraphics
Intel Core i5 2500K P67 Professional AMD Radeon HD 6950 unlock NVIDIA GeForce GTX 460 2gb 
RAMRAMHard DriveHard Drive
G.Skill Ripjaws G.Skill Ripjaws Intel X25-V Seagate Barracuda 
Hard DriveOptical DriveOSMonitor
WD Goflex USB 3.0 24x DVD R/W DL Win7 Ultermate 64 Acer 20in 1600x900 
MonitorMonitorMonitorKeyboard
Compaq 20in 1600x900 17in Dell 1280x1024 19in Gateway 1280x1024 Razer Blackwidow mech w/ cherry MX blues 
PowerCaseMouseAudio
Kingwin LZ-750 HAF 932 + sound activated lights Logitech G500 Rosewill USB headset 
CPUMotherboardGraphicsRAM
Pentium 4 3.2ghz w/ HT HP Intel IGP 4gb Mushkin DDR2 
Hard DriveOSPowerCase
80gb sata WinXP Pro HP OEM HP Small form factor 
  hide details  
Reply
The Butthurt Box
(21 items)
 
   
CPUMotherboardGraphicsGraphics
Intel Core i5 2500K P67 Professional AMD Radeon HD 6950 unlock NVIDIA GeForce GTX 460 2gb 
RAMRAMHard DriveHard Drive
G.Skill Ripjaws G.Skill Ripjaws Intel X25-V Seagate Barracuda 
Hard DriveOptical DriveOSMonitor
WD Goflex USB 3.0 24x DVD R/W DL Win7 Ultermate 64 Acer 20in 1600x900 
MonitorMonitorMonitorKeyboard
Compaq 20in 1600x900 17in Dell 1280x1024 19in Gateway 1280x1024 Razer Blackwidow mech w/ cherry MX blues 
PowerCaseMouseAudio
Kingwin LZ-750 HAF 932 + sound activated lights Logitech G500 Rosewill USB headset 
CPUMotherboardGraphicsRAM
Pentium 4 3.2ghz w/ HT HP Intel IGP 4gb Mushkin DDR2 
Hard DriveOSPowerCase
80gb sata WinXP Pro HP OEM HP Small form factor 
  hide details  
Reply
post #3 of 7
Quote:
Originally Posted by graphicsman View Post
I have always wondered when you read about a mobo that requires a CPU 4 pin connector do you always use the 4 volt rail from the psu in the specs description. Or when you read about psu specs it will indicate CPU 4 pin?
What PSU do you have that has a 4V rail? ATX 2.x standard only has 3.3V, 5V, and 12V. CPU using 12V.
DD Boxen
(23 items)
 
   
CPUMotherboardGraphicsRAM
Intel Xeon E3-1230 Asus Maximus IV Gene-Z/Gen3 Powercolor 6970 2GB G. Skill 1600mHz Ripjaws 
Hard DriveOptical DriveCoolingCooling
SpinpontF3 1TB, WD 250, and WD320 Lite-On DT Waterblocks DT5Noz Waterblock Swiftech Komodo 6900-1 Waterblock 
CoolingCoolingCoolingOS
Swiftech MCR-220 Drive radiator Swiftech MCR-220 QP radiator 6xGentle Typhoon AP-15s Archx64 KDE4.5, Windows 7 x64 
MonitorKeyboardPowerCase
Eyefinity 3-head 5265x1050 OCN Ducky!! MX Blue Switches XFX 750W Black Edition Mountain Mods H2gO 
MouseAudioAudioAudio
Razer Naga Asus Xonar Essence STX Sennheiser 595 Sony STR-DE995 A/V receiver 
OtherOther
Lian Li Card flash memory reader Asus PCE-N15 Wifi-N card 
CPUMotherboardGraphicsRAM
AMD 1055T Gigabyte 790 Sapphire 4850x2 2x2GB 1600mHz 
Hard DriveOptical DriveOSKeyboard
A few Yes Vista/7 Das Keyboard 
Power
Ugly 
CPUMotherboardGraphicsRAM
Qualcomm Snapdragon APQ8060 1.2 GHz Something kinda small Qualcomm Adreno core 16GB 
Hard DriveOptical DriveOSMonitor
None N/A WebOS 3.0.2 9.7" XGA, multitouch 
PowerCase
6300mAh Piano Black 
  hide details  
Reply
DD Boxen
(23 items)
 
   
CPUMotherboardGraphicsRAM
Intel Xeon E3-1230 Asus Maximus IV Gene-Z/Gen3 Powercolor 6970 2GB G. Skill 1600mHz Ripjaws 
Hard DriveOptical DriveCoolingCooling
SpinpontF3 1TB, WD 250, and WD320 Lite-On DT Waterblocks DT5Noz Waterblock Swiftech Komodo 6900-1 Waterblock 
CoolingCoolingCoolingOS
Swiftech MCR-220 Drive radiator Swiftech MCR-220 QP radiator 6xGentle Typhoon AP-15s Archx64 KDE4.5, Windows 7 x64 
MonitorKeyboardPowerCase
Eyefinity 3-head 5265x1050 OCN Ducky!! MX Blue Switches XFX 750W Black Edition Mountain Mods H2gO 
MouseAudioAudioAudio
Razer Naga Asus Xonar Essence STX Sennheiser 595 Sony STR-DE995 A/V receiver 
OtherOther
Lian Li Card flash memory reader Asus PCE-N15 Wifi-N card 
CPUMotherboardGraphicsRAM
AMD 1055T Gigabyte 790 Sapphire 4850x2 2x2GB 1600mHz 
Hard DriveOptical DriveOSKeyboard
A few Yes Vista/7 Das Keyboard 
Power
Ugly 
CPUMotherboardGraphicsRAM
Qualcomm Snapdragon APQ8060 1.2 GHz Something kinda small Qualcomm Adreno core 16GB 
Hard DriveOptical DriveOSMonitor
None N/A WebOS 3.0.2 9.7" XGA, multitouch 
PowerCase
6300mAh Piano Black 
  hide details  
Reply
post #4 of 7
Some PSU's feature a single rail design in which all the 12v+ share one strong rail..
Other PSU's with multiple rails will usually ( not always ) indicate the amperage available ( or what they claim ) on each rail.
post #5 of 7
Thread Starter 
Sorry I meant 12 volt four pin. I was trying to figure out if a 12 volt rail is supposed to go into the CPU 4 pin connection or is the PSU indicate it
OverKill
(18 items)
 
  
CPUMotherboardGraphicsGraphics
AMD Phenom II X6 1055T Gigabyte 890FXA ATI FirePro V3800 ATI FirePro V3800 
RAMHard DriveHard DriveOptical Drive
16gb GSkill 10666 Seagate Western Digital  LG Blue Ray 
CoolingOSMonitorMonitor
stock air 7 Pro 64 bit (2)22" Acer x223w (2)23" Acer G235H 
KeyboardPowerCaseMouse
Microsoft Wireless Antec 900watt Antec 300 Wacom Tablet 
Audio
Logitech Speakers and sub 
  hide details  
Reply
OverKill
(18 items)
 
  
CPUMotherboardGraphicsGraphics
AMD Phenom II X6 1055T Gigabyte 890FXA ATI FirePro V3800 ATI FirePro V3800 
RAMHard DriveHard DriveOptical Drive
16gb GSkill 10666 Seagate Western Digital  LG Blue Ray 
CoolingOSMonitorMonitor
stock air 7 Pro 64 bit (2)22" Acer x223w (2)23" Acer G235H 
KeyboardPowerCaseMouse
Microsoft Wireless Antec 900watt Antec 300 Wacom Tablet 
Audio
Logitech Speakers and sub 
  hide details  
Reply
post #6 of 7
The connection from the 4 pin on the motherboard will go to any of the compatible connectors on the PSU, your PSU manual (or markings on the PSU itself) will tell you which ones are the right ones. But usually modular PSUs only allow the right plugs in the right places, so find one where it fits comfortably without forcing.
Ryzen 5 1600
(12 items)
 
  
CPUMotherboardGraphicsRAM
AMD Ryzen 5 1600 MSI B350 Gaming Plus Gigabyte GeForce GTX 1060 WINDFORCE2 OC 16GB (2x8GB) Corsair DDR4 Vengeance LED, PC4-24... 
Hard DriveHard DriveCoolingOS
256GB Samsung PM961 Polaris M.2 NVMe  1TB Toshiba DT01ACA100 3.5" HDD, SATA III  Cooler Master Hyper 212 Evo Windows 10 64 
KeyboardPowerCaseMouse
Unicomp Model M 650W EVGA SuperNOVA G1, 80PLUS Gold, Full Modular Kolink Luminosity Cooler Master Reaper Aluminium 
  hide details  
Reply
Ryzen 5 1600
(12 items)
 
  
CPUMotherboardGraphicsRAM
AMD Ryzen 5 1600 MSI B350 Gaming Plus Gigabyte GeForce GTX 1060 WINDFORCE2 OC 16GB (2x8GB) Corsair DDR4 Vengeance LED, PC4-24... 
Hard DriveHard DriveCoolingOS
256GB Samsung PM961 Polaris M.2 NVMe  1TB Toshiba DT01ACA100 3.5" HDD, SATA III  Cooler Master Hyper 212 Evo Windows 10 64 
KeyboardPowerCaseMouse
Unicomp Model M 650W EVGA SuperNOVA G1, 80PLUS Gold, Full Modular Kolink Luminosity Cooler Master Reaper Aluminium 
  hide details  
Reply
post #7 of 7
Quote:
Originally Posted by railfan844 View Post
Almost all psu's have 4 pin cpu connectors. Some of them also have 8 pin, which is just 2 x 4 pin (lower resistance and ripple, no actual power increase).
The 4pin has an artificial limit by ATX standards of 150w
The 8pin has an artificial limit by ATX standards of 300w

Using a 4+4 or 8pin design does not decrease ripple. It can lower resistance; though it depends on the cable design, pin crimping, connection security, ect. So just using the 8pin connection does not guarantee lower resistance.

Quote:
Originally Posted by graphicsman View Post
Sorry I meant 12 volt four pin. I was trying to figure out if a 12 volt rail is supposed to go into the CPU 4 pin connection or is the PSU indicate it
Well the socket you plug your cable into will always determin what voltages the cables (and thus connectors) carry.
You will never have a cable that can only carry 12v (as that would just be silly.)

Though most PSU's are designed so that 4pin/8pin CPU modular connectors are keyed so only the CPU power connector cables will work in them.

Same with SATA/Molex cables or PCIe 6pin/8pin cables.

Though yes, the CPU power connector only supplies 12v to the CPU.
Test Bed
(24 items)
 
TTTbox
(15 items)
 
 
CPUMotherboardGraphicsRAM
Core i5 3570K  Biostar TZ774XE Power Color AX5770 1GB 4x4GB 1866Mhz 9-10-9-27-2T 
Hard DriveHard DriveHard DriveHard Drive
Samsung Spinpoint F3 1TB Samsung Spinpoint F3 1TB Western Digital Green 2TB Samsung Spinpoint M4 500GB 
Hard DriveOptical DriveCoolingOS
Intel X-25M G2 80GB Lite-On BluRay Drive Arctic Cooling Freezer 13 Pro Windows 7 Ultimate 
MonitorKeyboardPowerCase
Dell U2212HM Deck Legend Frost Tactile Silverstone Strider Plus 750w Custom Acrylic Test Bed 
MouseMouse PadAudioAudio
Logitech G500 Cooler Master Storm Tactics FPS Beyer Dynamics DT-990 600ohm Samson MediaOne 3A 
AudioAudioOtherOther
FiiO E09k QOGIR FiiO E17 ALPEN Microsoft Lifecam Studio Blue Yeti Pro Microphone 
CPUMotherboardGraphicsRAM
AMD A10-A5800K ASRock FM2A85X-ITX Radeon HD7770 1GB 2x8GB 1866mhz C9 
Hard DriveHard DriveOptical DriveCooling
SanDisk Ultra Plus 128GB 2TB 5400 RPM  24x DVD Drive Noctua L9A 
OSMonitorKeyboardPower
Windows 7 Home Premium 32" IPS TV Logitech K400 Seasonic G360 
CaseMouseAudio
Cooler Master Elite 120 Advanced Logitech K400 Trackpad Custom 2.1 Home Theater Setup 
  hide details  
Reply
Test Bed
(24 items)
 
TTTbox
(15 items)
 
 
CPUMotherboardGraphicsRAM
Core i5 3570K  Biostar TZ774XE Power Color AX5770 1GB 4x4GB 1866Mhz 9-10-9-27-2T 
Hard DriveHard DriveHard DriveHard Drive
Samsung Spinpoint F3 1TB Samsung Spinpoint F3 1TB Western Digital Green 2TB Samsung Spinpoint M4 500GB 
Hard DriveOptical DriveCoolingOS
Intel X-25M G2 80GB Lite-On BluRay Drive Arctic Cooling Freezer 13 Pro Windows 7 Ultimate 
MonitorKeyboardPowerCase
Dell U2212HM Deck Legend Frost Tactile Silverstone Strider Plus 750w Custom Acrylic Test Bed 
MouseMouse PadAudioAudio
Logitech G500 Cooler Master Storm Tactics FPS Beyer Dynamics DT-990 600ohm Samson MediaOne 3A 
AudioAudioOtherOther
FiiO E09k QOGIR FiiO E17 ALPEN Microsoft Lifecam Studio Blue Yeti Pro Microphone 
CPUMotherboardGraphicsRAM
AMD A10-A5800K ASRock FM2A85X-ITX Radeon HD7770 1GB 2x8GB 1866mhz C9 
Hard DriveHard DriveOptical DriveCooling
SanDisk Ultra Plus 128GB 2TB 5400 RPM  24x DVD Drive Noctua L9A 
OSMonitorKeyboardPower
Windows 7 Home Premium 32" IPS TV Logitech K400 Seasonic G360 
CaseMouseAudio
Cooler Master Elite 120 Advanced Logitech K400 Trackpad Custom 2.1 Home Theater Setup 
  hide details  
Reply
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Power Supplies
Overclock.net › Forums › Components › Power Supplies › 12 volt rail question