# multiple 12V rails amperage issues (Neo HE 430 and 550)



## justpassingby (Mar 11, 2007)

How much can we really expect of a 12V rail in a multi-rail PSU ?

I come from this topic but since the discussion was leaning towards the PSU amperage and wattage, I brough it here. You should read linderman's answer which is very interesting, then the sticky up here about power supply information and selection, and also this and this about the multirails if you want all the info.

So I have this Antec NeoHE 430W (ATX 2.2) which boasts three 12V rails @ 16A each, for a max total output of 384W on the 12V rails. Read this review for its specs. And I have this rig with a P4 630 3.0Ghz cpu, a GeForce 7600GT (without a separated power connector) and a P5B Deluxe. _Will that PSU be able to power that system ?_

On the 4th page of the silentpc review, they tested the real output of the NeoHE 430 with a given system. 

```
DC Output Voltage (V) + Current (A)
   +12V1         +12V2          +5V          +3.3V        Output
11.85 13.45   11.76 11.50    4.86 11.00    3.23 17.00     425.1W
```
which makes 25A on the combined 12V rails. I don't know why they didn't test the 12V3 rail to see it's influence on the 2 other 12V rails. It still gives me the informations I need because I won't use a graphic card with a separated power cable nor will I use more than 2 sata drives, so I suppose my system would not use much of the third 12V rail.


*Questions :*
1) Could a different system be able to draw more amperage from that PSU, or do we have to consider 13.45A the maximum on one 12V rail ?

2) For my system, will the 12V2 rail (associated with the EATX12V connector on the motherboard in a 2.2 ATX PSU) be the only one powering both the CPU and the GPU or are the CPU and GPU powered by different 12V rails ? 
And for the detailled answer : 
a) Do the PCI cards on the mainboard draw their current from the 24pins power connector, from the 4/8pins one or from both ? 
b) Is it the same rail that powers the 24pins and 4/8pins motherboard connectors ? 

3) I'm in Europe and voltage here is 220V. Some reviews hint that a PSU might be more efficient with 220V input voltage than with 110V. Anyone can infirm or confirm ?

4) There seem to be compatibility issues between NeoHE 430 and Asus motherboards... my chance. Anyone knows about this with a P5B Deluxe ? I bought my PSU last August so I would have expected to have one of the newer models Antec manufactured to solve those problems. Where can you find the equivalent of a revision ID on a PSU and what revisions are having problems with Asus motherboards ? I'm waiting for a reply from Antec to the same question, but the sooner the better.

5) My local retailer's "biggest" PSU is the Antec NeoHE 550W. Would it be sufficient if the 430 isn't enough ? It's also a multirail PSU (three 12V rails @ 18A). Here's a test of the NeoHE 550's performances :

```
Total Load     3.3V Load    5V Load    12V-1 Load    12V-2 Load    12V-3 Load
100% (~550W)   23A (76W)   20A (100W)   13A (156W)   13A (156W)    5A (60W)
```
As with the 430, the amperage on the 12v rail is 13A, but the rig they used is wayyyy more demanding than mine. *How can they run a 7800GT on a 13A 12V rail when the typical 7600GT requirements are 20A on the 12V rail and when the NeoHE 550 specs indiquate 18A on the 12V rail ?*

I'm getting confused here, since linderman told me a rail specified for 18A could shut itself down if that limit was exceeded. I still don't get it with those multirails PSU's :4-dontkno (and I can't easily find a 500W+ single rail one in shops around here)


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## twajetmech (Jul 1, 2004)

1) Could a different system be able to draw more amperage from that PSU, or do we have to consider 13.45A the maximum on one 12V rail ?
The maximum draw on that rail will be 13.5A, however in reality if you come close or attempt to exceed that value the probability is that the rail will overload and the psu may shut down. this is common with the now in fashion multi-rail psu's....most high end psu mfg's are moving away from multi-rail and going back to single rail designs because of issues with demanding graphics cards

2) For my system, will the 12V2 rail (associated with the EATX12V connector on the motherboard in a 2.2 ATX PSU) be the only one powering both the CPU and the GPU or are the CPU and GPU powered by different 12V rails ? 
And for the detailled answer : 
the 24 pin connector powers the cpu and the mobo, thus it supplies power to the pci and pci-e slots....since it cannot supply enough power for many videocards out today most videocards have supplemental connectors to supply additional power....that would be froom a seperate rail, the problem then arrises as that rail is now tied up with the videocard and if the videocard does not draw the maximum value of that rail, the extra power available is not shared to the remaining rails, thus you could find yourself underpowered much easier that you thought.
a) Do the PCI cards on the mainboard draw their current from the 24pins power connector, from the 4/8pins one or from both ? 
see above comment
b) Is it the same rail that powers the 24pins and 4/8pins motherboard connectors ? 
see above comment

3) I'm in Europe and voltage here is 220V. Some reviews hint that a PSU might be more efficient with 220V input voltage than with 110V. Anyone can infirm or confirm ?
confirm, running a psu at 220V is more efficent that at 110V

4) There seem to be compatibility issues between NeoHE 430 and Asus motherboards... my chance. Anyone knows about this with a P5B Deluxe ? I bought my PSU last August so I would have expected to have one of the newer models Antec manufactured to solve those problems. Where can you find the equivalent of a revision ID on a PSU and what revisions are having problems with Asus motherboards ? I'm waiting for a reply from Antec to the same question, but the sooner the better.
The Neo incompatability with Asus mobo's was a while ago, and did not affect the P5B mobo, Antec has since revised its circuitry to make the Neo compatible with Asus mobo's affected

5) My local retailer's "biggest" PSU is the Antec NeoHE 550W. Would it be sufficient if the 430 isn't enough ? It's also a multirail PSU (three 12V rails @ 18A). 
I would guess your psu needs at a total draw of 400W using our normal psu reccomendation figures add 30% = 520W as the minimum psu for your rig. I would say that the PC P&C Scilencer 610W, Seasonic M12 600W, would fit your system requirements nicely.There must be online stores based in Belgium that carry such items...even Amazon EU might have it.


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## Kalim (Nov 24, 2006)

justpassingby said:


> How much can we really expect of a 12V rail in a multi-rail PSU ?


The ones that are _really_ multiple rails and have OCP will be limited to some value, usually 18A-21A. Many like the Antec TP3 Trio are *not* actually multi-railed as the line regulators and transformers are the same - one +12V. They are just split later on to show them as multi-railed, which means they can be overloaded beyond specification and will be able to handle the load to a point. The NeoHE 430 is actually a tri +12V rail so it will be limited.


> Will that PSU be able to power that system ?


Since your CPU is power hungry as P4's were, and can easily pull 120W (12Vx10A), I would go for higher. A simple test setup of:
2 x 512MB Crucial DDR-II 533 Dual Channel DIMMs 3-2-2-12
Intel 955X Motherboard
ATI Radeon X850 XT PCI Express
.. with your CPU was pulling 214Watts here.


> 1) Could a different system be able to draw more amperage from that PSU, or do we have to consider 13.45A the maximum on one 12V rail ?


 Something more power demanding can pull more watts on different rails but altogether, it will only go as far as the specs when it trips and shuts off to protect the PSU. Upto 32A on the +12V rails combined can be drawn if the rest of the rails are limited to just 46Watts. Whats known as "crossloading" and some PSU's perform perfect with that while others do not.


> 2) For my system, will the 12V2 rail (associated with the EATX12V connector on the motherboard in a 2.2 ATX PSU) be the only one powering both the CPU and the GPU or are the CPU and GPU powered by different 12V rails ?


 The ATX12V 20 or 24pin connector will power your CPU and GPU slots. You have a P4, which needs a ATX12V 4pin (P4 cable), and that provides the +12V to your CPU specifically and is on +12V2, so thats good. 


> And for the detailled answer :
> a) Do the PCI cards on the mainboard draw their current from the 24pins power connector, from the 4/8pins one or from both ?


From the on-GPU connectors and from the PCI slots through the 20/24 pin ATX12V connector.


> b) Is it the same rail that powers the 24pins and 4/8pins motherboard connectors ?


Not on the NeoHE 430W. Differs by PSU.


> 3) I'm in Europe and voltage here is 220V. Some reviews hint that a PSU might be more efficient with 220V input voltage than with 110V. Anyone can infirm or confirm ?


 Yes, definitely. More powerful VAC input.


> 4) There seem to be compatibility issues between NeoHE 430 and Asus motherboards... my chance. Anyone knows about this with a P5B Deluxe ? I bought my PSU last August so I would have expected to have one of the newer models Antec manufactured to solve those problems. Where can you find the equivalent of a revision ID on a PSU and what revisions are having problems with Asus motherboards ? I'm waiting for a reply from Antec to the same question, but the sooner the better.


From the person who has the incompatibility :tongue: They look at their manual and it will state the revision number of the PSU. Other than that, only others who've read this info accurately or Antec/ASUS themselves could confirm it. The info I know is the same as what twajetmech stated before me. I have a P5B Deluxe and never had a problem with any PSU yet, not even a NeoHE 550W.


> I'm getting confused here, since linderman told me a rail specified for 18A could shut itself down if that limit was exceeded.


Yup, he was 100% correct :sayyes: If it was limited, the protection will shut the PSU off at the stated power requirement.


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## justpassingby (Mar 11, 2007)

Thx for your anwsers twajetmech

I thought the 4/8 pin connector you found next to the processor was for powering the processor ? I'm not talking about the 6 pin connector for PCI-e cards that support one, my PCI-e card takes all its power from the pci-express slot. I want to know if the processor and the GPU are powered by the same rail with an ATX 2.2 PSU when the GPU hasn't got a supplemental connector.

Edit : Kalim replied (thx Kalim) while I was posting. From what you say I guess that the ATX12V 24 pin connector draws it's power from the 12v1 rail while the ATX12V 4/8 pin connector draws it from 12v2.
So let's say my P4 draws 8A from the 12v2 and my 7600GT draws ?A from the 12v1. Can it overload my NeoHE 430 ? (my system is actually stripped to MB, CPU, GPU and won't post)

_Any reactions to the 7800GT Pci-e working with a PSU that gives only 13A on its 12V rails in working conditions and that's rated for 18A maximum per rail ?_

Seasonic M12 600W is not cheap around here... 160€ for the lowest price, eq to 212$ at actual changes (it costs 165$ on newegg... I hate it when european retailers seem to use 1:1 conversion rate from USD to Euros)


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## justpassingby (Mar 11, 2007)

Brought back my computer to my retailer, the guy said that the NeoHE430 could in no way have trouble to power my rig. Said he had the same PSU running his Pentium 4 Extreme Edition and 7800GT since 1 year without problems. Again, I'm in Belgium, so 220 current input helps maybe.

He still seemed a bit concerned when I told him that if you used the three rails of a multi-rail psu, the amperage that's not used on each rail should be lost for the others. And he also didn't know about the usual recriminations on multi-rail PSU's in favor of single rail ones.


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## twajetmech (Jul 1, 2004)

http://www.amazon.co.uk/Sonic-M12-6...1?ie=UTF8&s=electronics&qid=1173996110&sr=8-5Not surprising, the psu is often the most neglected piece of pc hardware despite being the most important one. There is a big difference between a psu that will run a computer and one that will run it well for a long time with stability, your retailer must like living on the edge...a 130W cpu and a near 200W gpu, not factoring HD's, mobo, cdrw etc. with a 430W mid level psu....not a reccomendation you'll get here on this forum. I did notice Amazon UK (EU) has the seasonic and Antec trio at a more reasonable price than your retailer quoted, it may be the way to go if you want a good psu. Seasonic
Antec Trio


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## justpassingby (Mar 11, 2007)

thx for those clarifications

£111 at Amazon Uk for the Seasonic 600W is still equal to 162€ or roughly 215$. I don't think I'll find it easily for less than 210$ in Europe, and that's without any delivery rates added.


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## linderman (May 20, 2005)

I think its a factor of two main topics here as to your retailer.


#1) Kalim and I had a long conversation one day when I asked him (he has alot of european living experience) why many units that are regarded as high quality overseas are considered floppers here ? Kalim then demonstrated with hard evidence and testing the 230 volt power is favored by PSU's and will make what we consider a modest built unit efficiently. so in essence, the overseas voltage will get your 430 watt psu further down the road than here in the US with our 115 volt. The Hiper-R 580 is a perfect example; that unit is loved in the UK but its a modest performer here in the United States.

#2) I dont blame your retailer for not wanting to install more PSU in a top unit than the NEO 550 the cost of such units where you live is staggering!
but I really believe his decision is based heavier on cost than performance.

why dont you try a 550 if your retailer has one in stock ; install it in your machine and see if that cures the problem, could well be you just plain got a lame horse too ????? it happens now and then to all brands.


topic #8

http://www.pcpower.com/technology/myths/


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