PC Peripherals Dual 12V Output - Why is this introduced

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Quad Master

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Hi Guys

Dual 12V Output - Why is this Dual 12V line introduced.
Can you guys explain me the reason behind having 2 12V lines

Just saw the new Antec PSU's with Dual Power 12V lines

Link:- http://www.antec.com/us/pro_powerSupply.html

Are this Dual power Antec Smart Power 2.0 PSU's available here

Me looking for SL450 or SL500 , ne one knows whats the approx cost.
SL 450 gives 15A + 17A on 2 x 12V Lines
SL 500 gives 17A + 19A on 2 x 12V Lines
Really gr8 now who requires True Power Series when you get enuf Amp on
Smart Power Series.

Hope i am not starting too many new threads but i like to get my doubts
cleared.
 
Dual 12V r to take the load seperately, ie indivisually for GFX, cpu nd the othr way u assign it ...thts wht i knw....but those words dnt explain it nice i think ;)

Prime ABGB said tht those wud b available in a month the last time i checkd.........was bout a month ago......so call em nd let us know too :D
 
I think hardyboy/techboy just bought one and he claims to have 25A on the 12V so i think its that only...

edit Just checked... Its SL450 ver 1.0 allright... and Smart power 2.0 is SP450 not SL450...
 
Dual 12V helps in isolating the CPU(and other mobo components) and I/O power. So either of them doesnt affect the other. Helps in giving a cleaner supply to the devices on the motherboard. May lead to better overclocks ;). The PC power and cooling 850W PSU has 4 12V rails :P.
 
Dual 12V rails are part of the new ATX version 2.0 Power Supply guidelines

Here's a PDF file on the ATX 2.0 guideline from formfactors.org:

http://www.formfactors.org/developer%5Cspecs%5CATX12V_PSDG_2_2_public_br2.pdf

I quote from there:

System components that use 12V are continuing to increase in power. In cases where expected current requirements is greater than 18A a second 12 V rail should be made available. ATX12V power supplies should be designed to accommodate these increased +12 VDC currents.
Click to expand...

In other words, this looks to be a measure to enhance safety and quality of power output.

One rail - the 12V1 rail is normally reserved for the 24-pin motherboard connector and the rest of the system.

The other - 12V2 rail is directed to the 4-pin 12v connector which is where the CPU draws its power from.

So by splitting the rails, you ensure quality power output to CPU / Rest of the system and also safety is ensured since high inrush current isnt sent through a single 12v rail.

One disadvantage to this system is, the power from both the 12V rails is not necessarily "shared". Lets say you have an Antec SP 450W PSU with a 12V1 rating of 15A and a 12V2 rating of 17A, your CPU will have a max of 17A alone at its disposal, even if the 12V1 rail has a few extra amps on it to spare.

What this means is, you cannot add up the Amps on both the 12v line and think you have 15 + 17 = 32A at your disposal on the 12v line. If your CPU cannot get the juice it needs from your 12V2 line, it will be starved of power and the 12V1 line cannot help. This is especially a problem during bootup when current draw is the most.

It is upto the PSU manufacturer to implement circuitry that shares the power between the two rails or not. So far only OCZ alone has specifically mentioned that the power is shared between the two rails on their PSUs. So do take into consideration individual rail current capacity when buying your PSU. (P.s: I thank JediMaster for enlightening me with this important bit of info :) )

I forgot to mention, mailed ITDepot about a week or so back (around the same time i was looking for a PSU), and surprisingly they mentioned the version 2.0 power supplies are expected within 3 weeks! :D
 
The new G70 is rumoured to require a minimum of 26A on the 12v line.If that is not exaggerated,then most psus,excluding top of the line antecs(>450w) will fail.
 
undertaker said:
The new G70 is rumoured to require a minimum of 26A on the 12v line.If that is not exaggerated,then most psus,excluding top of the line antecs(>450w) will fail.
Click to expand...

PSU's will cost a bomb here after G70 comes here.
As those who will put a G70 based Gpu will have to spend first on a better PSU.

Edit Added Later

Crazy_Eddy said:
One disadvantage to this system is, the power from both the 12V rails is not necessarily "shared". Lets say you have an Antec SP 450W PSU with a 12V1 rating of 15A and a 12V2 rating of 17A, your CPU will have a max of 17A alone at its disposal, even if the 12V1 rail has a few extra amps on it to spare.
What this means is, you cannot add up the Amps on both the 12v line and think you have 15 + 17 = 32A at your disposal on the 12v line. If your CPU cannot get the juice it needs from your 12V2 line, it will be starved of power and the 12V1 line cannot help. This is especially a problem during bootup when current draw is the most.
Click to expand...

Guys after reading Eddy's this part of post
What do you feel a single 12V PSU is better or still you feel Dual 12V is better.

I am in a state of confusion. :huh:
What will you suggest a Single or Dual 12V line PSU for my new rig.
 
Quad Master said:
PSU's will cost a bomb here after G70 comes here.
As those who will put a G70 based Gpu will have to spend first on a better PSU.

Edit Added Later

Guys after reading Eddy's this part of post
What do you feel a single 12V PSU is better or still you feel Dual 12V is better.

I am in a state of confusion. :huh:
What will you suggest a Single or Dual 12V line PSU for my new rig.
Click to expand...

Wait for the dual 12V rail. Atleast in the states, they cost the same. I hope its the case here as well ;)
 
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