Why a single rail power supply is superior to multiple rails

[jonnyGURU]

Originally posted by: Howard
Certain limitations can happen. I believe I came across one such issue when researching the Enhance ENP-5140GH (model # off the top of my head), 12V1 was limited to 16A and 12V2 was limited to 18A, with 32A total. IIRC, 12V2 was for CPU and 12V1 was for mobo/graphics.

Let's see if I care enough to check that now...

EDIT: I was right about everything about maybe CPU - the full 8-pin connector draws from both 1 and 2, when split, it's probably only 2 that it draws from.

I think Enhance is the only PSU's I've seen with an even split. But usually it's the connector with the lower number that provides power to the CPU and whether it's a 4-pin, 8-pin or a 4+4-pin, typically they draw power from the same rail.

If they're going to follow the ATX12V specification with limits on rails, they're usually going to also follow the part about putting the CPU on it's own rail.

 

[Howard]

Well, the wiring diagram shows the 8-pin connector having both 12V1 and 12V2 leads.

 

[jonnyGURU]

Originally posted by: Howard
Well, the wiring diagram shows the 8-pin connector having both 12V1 and 12V2 leads.

REALLY? That's VERY strange for a PSU with two +12V rails. Usually they do that for four or more +12V rails, but even then each of those rails are only for CPU power and nothing else.

Do you have a link to this wiring diagram?

EDIT: Also, where did you find that it was 32A combined? The one I had only had 28A available on the +12V and I confirmed this with someone at Enhance.

EDIT2: I also just pulled up the PDF for Enhance EN-5100 series and it shows all CPU power on +12V2 (which is 15A, not 14A.)


EDIT3: You must be looking at the PDF on the U.S. site. So not only do we have contradiction from Enhance on the total +12V output, but also one what connector gets power from what rail.

 

[Howard]

Yes, that's the one. If you could clear that up, that would be nice. I didn't really want to recommend the unit(s) at the time because the video cards only got 16A less drive/mobo juice to play with.

 

[jonnyGURU]

Originally posted by: Howard
Yes, that's the one. If you could clear that up, that would be nice. I didn't really want to recommend the unit(s) at the time because the video cards only got 16A less drive/mobo juice to play with.

That's cool. But I already confirmed the combined +12V with the guy at Enhance (I think you've talked to the same guy in the past.) Haven't seen any other rating posted anywhere else.

The document I'm going off of for the 4-pin and 8-pin connector is actually from Enhance Taiwan w/ no marketing fluff. I had requested it when I was interested in using them as an OEM. Unfortunately, one has to compete against eWiz's "OEM" Enhance units when using Enhance as an OEM and that's something I just didn't want to do.

 

[Howard]

So what's the news about the rail allocation, then?

 

[jonnyGURU]

Originally posted by: Howard
So what's the news about the rail allocation, then?

Originally posted by: jonnyGURU
I also just pulled up the PDF for Enhance EN-5100 series and it shows all CPU power on +12V2 (which is 15A, not 14A.)

Originally posted by: jonnyGURU
The document I'm going off of for the 4-pin and 8-pin connector is actually from Enhance Taiwan w/ no marketing fluff.