Dual +12V vs single +12v

[JEDIYoda]

Im fixing to get a new PSU was wondering why I see some Power supplies with a dual +12V and others with a single?

Most of the reviews I have read on power supplies make little if any mention of whether the power supply is dual or single?

Are we talking apples and oranges?

Or is this somerthing that just has`nt become the norm yet?

Thank for any replies!!

I have been looking at this power supply--
http://www.directron.com/aeropower550.html

I also noticed that no matter what kind of question is asked somebody always mentions a fortron power supply.
I understand they are good!!
I also understand there are alot of good power supplies on the market......boy can this get confusing...lolol

 

[Bona Fide]

A dual +12V rail is primarily for safety/stability purposes. By distributing the load across two rails, there's a less chance that the PSU will overload and burn out. This comes at the cost of some amperage, but most companies are good about that nowadays.

Get a single +12V rail if you want raw power, and are willing to risk overload. Get dual +12V rails if you're okay with slightly less power, but value safety and stability.

In either case, there's only a few PSU brands that you should actually consider.

- Antec
- OCZ
- Seasonic
- FSP Group (Fortron)

 

[albumleaf]

Actually dual rail psus generally have MORE amperage total on the 12v rails. Check out the xclio 450 watt psu at newegg. It's only $52 and has 32A across both rails combined... not to mention that it's an OEM Antec basically.

 

[Bona Fide]

Originally posted by: albumleaf
Actually dual rail psus generally have MORE amperage total on the 12v rails. Check out the xclio 450 watt psu at newegg. It's only $52 and has 32A across both rails combined... not to mention that it's an OEM Antec basically.

No.

With dual rails, there's bound to be some overhead. 18A + 18+ will NOT give you 36A. It's actually closer to 32A. On a single-rail setup, you know exactly what you'll be getting, which is slightly beneficial. But if there's at least 15A on each rail in a dual-rail setup, you should be fine.

 

[Navid]

Originally posted by: albumleaf
Actually dual rail psus generally have MORE amperage total on the 12v rails. Check out the xclio 450 watt psu at newegg. It's only $52 and has 32A across both rails combined... not to mention that it's an OEM Antec basically.

That may be. But, you cannot always combine!
The current of each rail can never go over its maximum even if the other rail is not loaded at all! So, if each rail can provide a maximum of 15A and you need 16A from one of the rails, you are out of luck even though the total Amp is 30A.

So as Bona Fide said, a dual-rail is good for safety and isolation of the two rails, which may be beneficial for overclocking, while a single-rail is good for flexibility and more power on a single rail, which again may be good for overclocking.

 

[Zepper]

Single rail is much more flexible. With split rail, you almost always won't be able to use all the +12 you have available w/o using custom adapters to tap the CPU rail. Unfortunately most of the lower powered PSUs that conform to the needs of modern systems (which means a larger portion of total power available on +12) have gone to the split rail. Split rail is mainly for safety as more than 20A of +12 available on one rail can be dangerous - but mainly to the inattentive. I don't know about you but I don't grab my +12 line while standing in a tub of water.
. I've been recommending the Sparkle FSP550-60PLG for a single rail PSU that can cover just about any system's needs and has full range AC regulation with active PFC. About $85. per Froogle. But it is gross overkill for most systems. Some of the TT models of around 420 or 480 are also nice single-rail models but I think they lack the aPFC and full range AC features of the Sparkle.
. And there are always the Zippy 600 and 700 models if you need really over the top PSUs and are willing to pay the freight.

.bh.

 

[Bona Fide]

Originally posted by: Zepper
Single rail is much more flexible. With split rail, you almost always won't be able to use all the +12 you have available w/o using custom adapters to tap the CPU rail. Unfortunately most of the lower powered PSUs that conform to the needs of modern systems (which means a larger portion of total power available on +12) have gone to the split rail. Split rail is mainly for safety as more than 20A of +12 available on one rail can be dangerous - but mainly to the inattentive. I don't know about you but I don't grab my +12 line while standing in a tub of water.
. I've been recommending the Sparkle FSP550-60PLG for a single rail PSU that can cover just about any system's needs and has full range AC regulation with active PFC. About $85. per Froogle. But it is gross overkill for most systems. Some of the TT models of around 420 or 480 are also nice single-rail models but I think they lack the aPFC and full range AC features of the Sparkle.
. And there are always the Zippy 600 and 700 models if you need really over the top PSUs and are willing to pay the freight.

.bh.

If you're in the market for a single-rail PSU for cheap, try OCZ's Modtream450. It's ~$70 at Newegg and other retailers. Lots of power, I think 36A on the 12V rail.

 

[EatSpam]

Originally posted by: Zepper
And there are always the Zippy 600 and 700 models if you need really over the top PSUs and are willing to pay the freight.

The Zippy 700W is a big one - I have one powering an entire system including 18 drives and it doesn't break a sweat.