charltonhua
New Member
Hello everyone. I was wondering what +12v rails on power supplies do? is there a definition of it?
+12v rails
- Thread starter charltonhua
- Start date
Dont know what you mean by what they do. The 12V leads off the power supply, power all the 12V hardware on your computer. Some power supplies have a single big 12V rail. Some split it up and have multi smaller rails.
Drenlin
Active Member
Computers use three different voltages- 12V, 5V, and 3.3V. The 5v and 3.3v aren't used as much, and can usually be ignored...an underpowered +5v/+3.3v rail is very rare. There's also a -12v rail, but it's not used a lot either and is typically ignored as well.
The +12v rail, however, needs to have a lot of power in it, as that's what most of the components use most. What you see in a lot of cheap PSU's is that they'll rate the whole unit for, say, 550W, but the +12v rail can only put out 450W or so. In a better PSU you'll see that the +12V rail is usually rated close to what the entire unit is rated for...sometimes even above it.
Like he said, sometimes the unit has multiple +12v rails instead of one big one. Two is most common in multi-rail systems. A lot of people don't like this because it can lead to an imbalance of power if everything gets connected to one rail on accident. You can end up with one rail being overloaded, and the other one doing almost nothing. There are also cases where one rail is only for the CPU, which usually leaves an excess of wattage available for the CPU, and not enough for everything else. You don't have to worry about any of that with a single rail. Now I'm not going to say that all multi-rail systems are bad, because they're not, but you definitely have to choose them carefully.
By the way, there ARE times, that multi-rail PSU's are good, like when you have a monster 1000W(or more!) power supply...you don't want to have to push all of that through one rail.
The +12v rail, however, needs to have a lot of power in it, as that's what most of the components use most. What you see in a lot of cheap PSU's is that they'll rate the whole unit for, say, 550W, but the +12v rail can only put out 450W or so. In a better PSU you'll see that the +12V rail is usually rated close to what the entire unit is rated for...sometimes even above it.
Like he said, sometimes the unit has multiple +12v rails instead of one big one. Two is most common in multi-rail systems. A lot of people don't like this because it can lead to an imbalance of power if everything gets connected to one rail on accident. You can end up with one rail being overloaded, and the other one doing almost nothing. There are also cases where one rail is only for the CPU, which usually leaves an excess of wattage available for the CPU, and not enough for everything else. You don't have to worry about any of that with a single rail. Now I'm not going to say that all multi-rail systems are bad, because they're not, but you definitely have to choose them carefully.
By the way, there ARE times, that multi-rail PSU's are good, like when you have a monster 1000W(or more!) power supply...you don't want to have to push all of that through one rail.
Last edited:
xxartanisxx
New Member
Hey Dren how would distribute 4 +12 V rails??
Like one to processor one to motherboard/ram one to video card and others to ODD/HDD & Fans?
Or am i not following this at all?
Thinking about using this one http://www.newegg.com/Product/Product.aspx?Item=N82E16817153106
Like one to processor one to motherboard/ram one to video card and others to ODD/HDD & Fans?
Or am i not following this at all?
Thinking about using this one http://www.newegg.com/Product/Product.aspx?Item=N82E16817153106
Drenlin
Active Member
Depends on how it's set up. I think it'd be more likely for it to be one for the CPU/Mobo/RAM, two for video cards, and one for everything else.That's rated at 216W per rail, which leaves a bit of headroom for the CPU/Mobo/etc, and a LOT of headroom for the hard drives and other peripherals. You may be right though, and two of the rails could be for the CPU and the Mobo/etc...which leaves only 432W for everything else.
charltonhua
New Member
yea that part where it states single, 2,4,6 rails on a +12v im not sure what that does.. so if im getting this correctly, are you saying that it just splits the power up?