PSU, enough Amps on 12V rail?

historian88 · Aug 31, 2014

I've read that for the GTX780 you need 42 amps on the 12v rail. Will I have enough? On the label for my psu, it says:
+12VA-18a
+12VB-18a
+12VC-18a
+5V-20a
+3.3V-20a
-12V-0.5a
+5VSB-4a

It also says "Max. Combined Power on +12VA & +12VB & +12VC output is 500W."

How does one go about calculating amps anyway?

oczdude8 · Aug 31, 2014

power is Voltage*Current (P=V*I). Knowing the voltage is 12v and power 500w, 500W/12v = 41.67A

Your maximum combined current on 12v is 41.67A. This may or may not be good enough. What is your psu model and what are your system specs?

Your psu is multirail and it can fail depending on how you connect the wires.

Delroy Monjo · Aug 31, 2014

A GTX 780 also requires Two 8-pin PCI Express power connectors or four available 6-pin PCI Express power connectors.
That 42A. power supply requirement is actually referring to the entire computer setup, not just the video card as the GTX780 itself will never likely draw more than 22A. but as oczdude8 says, when drawing that kind of power from 3 different rails in the PSU you won't really be sure how the power is distributed.
I wouldn't recommend using a 500W PSU with a GTX780.

BRUTALSALAMANDER · Sep 23, 2014

I would invest in a Modular 600-700watt PSU to be sure than you have enough on the +12v rail this one for example http://www.ebuyer.com/545317-corsair-rm-650w-fully-modular-80-gold-power-supply-cp-9020054-uk will have more than enough connectors and have plenty of headroom left. It is also 80+ certified so it will be very reliable and not drop voltage below 80% so it will be a good invest for your shiny new card.

ko888 · Sep 23, 2014

historian88 :

That Delta Electronics PSU should be fine. It already has the appropriate 75 Watt 6-pin and 150 Watt 8-pin PCI Express supplementary power connectors. Each PCI Express supplementary power connector should be wired to a different +12V rail.

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PSU, enough Amps on 12V rail?

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