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Will multiple 12V rails on a psu affect power support?

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November 26, 2013 1:47:11 PM

If i get a psu with 4 +12V rails at 20A each and i get a graphics card, like the GTX 780, and it requires 42A on the +12V rail, will that psu be able to properly support and power the graphics card?
a b ) Power supply
a b U Graphics card
November 26, 2013 2:14:31 PM

You will get the molex adapters with the graphics card so you can split the power over 2 or more rails. Each rail will share the load. So you PSU will power the card.
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a c 1203 ) Power supply
a c 564 U Graphics card
November 26, 2013 2:19:45 PM

DarkDubzs said:
If i get a psu with 4 +12V rails at 20A each and i get a graphics card, like the GTX 780, and it requires 42A on the +12V rail, will that psu be able to properly support and power the graphics card?


If the multi +12V rail PSU is properly designed you don't need to worry about it.

What is the specific brand and model of the PSU that you are considering?
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a b ) Power supply
a b U Graphics card
November 26, 2013 2:20:46 PM

DarkDubzs said:
If i get a psu with 4 +12V rails at 20A each and i get a graphics card, like the GTX 780, and it requires 42A on the +12V rail, will that psu be able to properly support and power the graphics card?


assuming its a quality PSU, you will have no issue
your single 12v rail is split into 4 so the split is often set up as such

12v1 - CPU
12v2 - mobo
12v3 - PCI-E 1
12v4 - PCI-E 2

sometimes the 12v1 is the mobo and 12v2 is then the CPU

what PSU are you looking at?
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November 26, 2013 2:28:19 PM

The psu im talking about is the EVGA SuperNova Bronze 750W. Sorry, should have said which psu i was talking about in the first place
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a c 288 ) Power supply
a c 202 U Graphics card
November 26, 2013 2:48:56 PM

Page six of the manual tells you how the connectors are laid out on the rails,
https://www.evga.com/support/manuals/files/120-PB-0750....

Also, read the link in my sig below, i covered multirail vs single rail a while ago, it really doesn't matter, a PCI-E GPU shouldn't be consuming more than 25A total, 6.25A of which will come from the motherboard via the PCI-E slot. Your PSU has one set of PCI-e connectors on 12V2 and the other two on 12V4. The GTX 780 has a power draw of 250W(20.83A) so even if you use two connectors from the same rail the motherboard is picking up some of that load on a separate rail and you will be perfectly fine, it is an intelligently laid out PSU.
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