Triple Rail PSU

Jamielicious

Jamielicious

Jamielicious

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25 Jul 2014
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I'm a little confused by my PSU and how it's specced.

Basically I have a "triple rail" PSU with 3 12V rails.

The 3 rails are specced as follows:

12V1: 16A
12V2: 25A
12V3: 17A

Does this mean I have 58A to play with when looking at graphics cards?
 
And what about the other 12volts needed for rest of hardware like Mobo/HDD's etc etc?

What is the exact maker and m del of your PSU?
 
It means that one of your rails can take 25A max draw

one rail can take 16A max draw

and the other can take 17A max draw


So you have to spread your equpiment out across the different rails.


Look up the max Amp draw of the card to want to buy (plus any overclock) if that is more than your 25A rail, then the psu is not enough.
 
I can see why they got rid of the multirail psu now.

Anyway I found this:
https://forum-en.msi.com/faq/article/printer/power-requirements-for-graphics-cards

So the 970 seems to want 28A.

My current card is a 7870, which is listed at 23A, however I'm running the windforcex3 version which has a 10% overclock.

My card before that was a 460, that's listed at 26A, however I overclocked that by 22%.

Before that I had the 4870, that's listed at 32A and I overclocked it by 10%.

So overall I seem to have gone for cards with similar power needs to the 970 and ran them fine on this psu. Does this mean that the 2 PCI-E cables run off different rails?
 
Your PSU is not a brand I've ever heard of and I can't find tech specs on it.

A GPU will draw a max of 75W (6.25A) from the motherboard. In the case of a 970, it has two 6 pin PCIe connectors for another 75W each (maximum) so the max it is allowed to draw is 6.25*3 = 18.75A.

There is then power for the CPU (for a 4770k, 84W, so 7A)

The problem with multirail PSUs is that you need to balance all this out across the rails. It may be that your 24 pin ATX plug, 4/8pin CPU plug, and 6pin PCIe plugs are distributed well, it may be they are distributed badly and overloading one rail. We can't tell!

However given the cards you've already run on the PSU, and given that my 980 SLI system never draws more than ~520W, I'd say you are fine.
 
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