PSU current

October 13, 2015

So I'm looking at buying a new power supply. I want to upgrade my current EVGA 600B to something modular with black sleeved wires and maybe around 700W.

I know that watts however is not the whole story, it's important to make sure you're going to have sufficient current on your 12V rail.

I do plan to upgrade my GPU within the next year and I've seen power supplies that I'm interested in range from 25A to 50A on the 12V rail.

My question is, how many Amps do I really need for a modern GPU. I know every brand / model is going to vary in it's power requirements, but I have found that Amp requirement is something that gets left out of a lot spec sheets. For example, what current does a reference GTX 980 draw? Is there a good rule of thumb for how much current you need in this day and age?

My specs are below, I am overclocking but I'm not powering any pumps or any demanding accessories.

STRMfrmXMN · October 13, 2015

So I'm looking at buying a new power supply. I want to upgrade my current EVGA 600B to something modular with black sleeved wires and maybe around 700W.

I know that watts however is not the whole story, it's important to make sure you're going to have sufficient current on your 12V rail.

I do plan to upgrade my GPU within the next year and I've seen power supplies that I'm interested in range from 25A to 50A on the 12V rail.

My question is, how many Amps do I really need for a modern GPU. I know every brand / model is going to vary in it's power requirements, but I have found that Amp requirement is something that gets left out of a lot spec sheets. For example, what current does a reference GTX 980 draw? Is there a good rule of thumb for how much current you need in this day and age?

My specs are below, I am overclocking but I'm not powering any pumps or any demanding accessories.

EVGAs B2/GS/G2 would be perfect for that, especially the G2 with its sleeved black cables.

Naeaes · October 13, 2015

The sad thing is that in addition to make and model, even individual units draw different wattages.

For the purposes of these kinds of calculations it's well safe enough to assume that Watts are Volt-Amperes. You can just divide the given Watts with 12V to get the Amps.

According to geforce.com a reference GTX980 draws 165W. So:

165W / 12V = 13,75A

And that's your answer.

The other way to look at this is to recognize that ATX and EPS12V are standardized systems. By those standards a 6-pin PCI-E supplementary power connector must deliver 75 Watts and a 8-pin one must deliver 150 Watts and the PCI-E-data connector on the motherboard must also be able to provide 75W. With that knowledge and a bit of trust in your manufacturer of choice you can make the assumption that if it has the necessary connectors and is marketed as ATX/EPS12V-compliant, it'll work.

October 13, 2015

The sad thing is that in addition to make and model, even individual units draw different wattages.

For the purposes of these kinds of calculations it's well safe enough to assume that Watts are Volt-Amperes. You can just divide the given Watts with 12V to get the Amps.

According to geforce.com a reference GTX980 draws 165W. So:

165W / 12V = 13,75A

And that's your answer.

The other way to look at this is to recognize that ATX and EPS12V are standardized systems. By those standards a 6-pin PCI-E supplementary power connector must deliver 75 Watts and a 8-pin one must deliver 150 Watts and the PCI-E-data connector on the motherboard must also be able to provide 75W. With that knowledge and a bit of trust in your manufacturer of choice you can make the assumption that if it has the necessary connectors and is marketed as ATX/EPS12V-compliant, it'll work.

All good info, thanks.