Sign in with
Sign up | Sign in
Your question
Solved

+12v rail amp question

Last response: in Components
Share
May 25, 2012 3:02:12 PM

I have an Antec Truepower New 750w PSU and currently also have a GTX 670 being shipped to be. I read somewhere that the GTX 670 requires a minimum of 30 amps on +12v rail.

The truepower has 4x +12v rails @ 25 amps each.

My questions is do the +12v rail amps add together?
Will the GTX 670 work on the PSU?

Thanks.

More about : 12v rail amp question

Best solution

a b ) Power supply
May 25, 2012 3:09:34 PM

They recommend 30A combined for the GPU, CPU, fans and other system devices using requiring 12V power. The 670 requires around 15Amps at max power if you don't overclock it.

Most PSUs are designed as to bridge this power over the rails if necessary. Even if yours doesn't, your CPU and motherboard will get their power from separate rail(s) than that which powers your GPU.

You'll be fine.
Share
May 25, 2012 3:18:00 PM

ubercake said:
They recommend 30A combined for the GPU, CPU, fans and other system devices using requiring 12V power. The 670 requires around 15Amps at max power if you don't overclock it.

Most PSUs are designed as to bridge this power over the rails if necessary.

You'll be fine.


Thanks for the response.

I found this on the Antec site for my PSU: +12V1, 12V2, 12V3, 12V4 max. load: 62A(744W).

It says the max amps load is 62. This leads me to believe the 4 separate rails share a common output of the sum of their amps? Is that how it works?
m
0
l
Related resources
a b ) Power supply
May 25, 2012 3:20:32 PM

Yeah. Though the individual rails can provide 25A, there is a max of 62A for all 12V rails.

So, basically, they're telling you they don't add to 100A over the 12V. Otherwise you'd have 1200W available just on the 12V!
m
0
l
May 25, 2012 3:27:48 PM

ubercake said:
They recommend 30A combined for the GPU, CPU, fans and other system devices using requiring 12V power. The 670 requires around 15Amps at max power if you don't overclock it.

Most PSUs are designed as to bridge this power over the rails if necessary. Even if yours doesn't, your CPU and motherboard will get their power from separate rail(s) than that which powers your GPU.

You'll be fine.


I think I get it now, so GPU might get a whole rail dedicated to itself. Then the CPU and other components that use +12v will use the other available +12v rails?

Is there any documentation you know of that specifies the recommend amps for the GTX670 you could link? I know you said 15A and you are probally right but I just want to see for myself out of curiosity.

Thanks
m
0
l
a b ) Power supply
May 25, 2012 3:31:12 PM

Simo606 said:
I think I get it now, so GPU might get a whole rail dedicated to itself. Then the CPU and other components that use +12v will use the other available +12v rails?

Is there any documentation you know of that specifies the recommend amps for the GTX670 you could link? I know you said 15A and you are probally right but I just want to see for myself out of curiosity.

Thanks

http://www.geforce.com/hardware/desktop-gpus/geforce-gt...

It shows the requirement of a 500W PSU when using a GTX 670. This is an estimate based on the fact that most modern power supplies with this much wattage will have enough Amps on the 12V rail(s) to power a system with a GTX 670 in it.
m
0
l
a b ) Power supply
May 25, 2012 3:35:18 PM

I get the 15A just using the simplified power equation:

Watts=Volts * Amps

Knowing the GTX 670 at max power requires 170W (from geforce specification page) on the 12V rail, I can divide the Volts from both sides of the equation to get the Amps necessary.

Amps=Watts/Volts

170W/12V=14.16A

Always round up!
m
0
l
May 25, 2012 3:36:24 PM

Best answer selected by Simo606.
m
0
l
May 25, 2012 3:40:04 PM

ubercake said:
I get the 15A just using the simplified power equation:

Watts=Volts * Amps

Knowing the GTX 670 at max power requires 170W (from geforce specification page) on the 12V rail, I can divide the Volts from both sides of the equation to get the Amps necessary.

Amps=Watts/Volts

170W/12V=14.16A

Always round up!


It's only since today that amps came into the equation for me since I stumbled across some random forum saying GTX670 req 30A. I then go and check my PSU and its only 25A per rail so got a bit worried haha.

That's a good eqation there, I will have to use that as a guide in the future, very handy indeed!

Thanks alot for your help. Really helpful and willing to offer advice.
m
0
l
a b ) Power supply
May 25, 2012 3:41:50 PM

Your power supply will do the job no problem. Since Amps.=Watts/Votage; the card is rated at 170w/12v=14.2A. Nvidia says 500w min. Your PSU is a very good 750 that can power two of these cards in SLI without breaking a sweat.
m
0
l
May 25, 2012 3:43:34 PM

Dogsnake said:
Your power supply will do the job no problem. Since Amps.=Watts/Votage; the card is rated at 170w/12v=14.2A. Nvidia says 500w min. Your PSU is a very good 750 that can power two of these cards in SLI without breaking a sweat.


That's great to hear. Here I was thinking I didn't have enough but turns out I have more than enough to do the job.
'
Thanks a bunch
m
0
l
!