Power supply + GPU question!

[-smash-]

So, my PSU's output power looks like this:

730 Watts, +3.3V@24A, +5V@30A, +12V1@18A, +12V2@18A, +12V3@18A, +12V4@20A, [email protected], [email protected]

I own a GTX 470 video card, and the power specs for the card state "Minimum of a 550 Watt power supply. (Minimum recommended power supply with +12 Volt current rating of 38 Amps.)"

I don't understand power supplies at all. Is my current PSU sufficient enough to run my 470?

I ask because I have some pretty apparent performance issues across some of my games, and I've done just about everything on the software side to try and fix the problem.

My PSU
Video card

 

[Asus]

I would think it should work fine.
6-pin plug is 75w (6.25A x 12v = 75W)
GTX 470 has 2 6-pin plugs right? Looks like they are on their own rail or share 1 which is fine (6.25A + 6.25A < 18A)
PCI-Express slot provides another 75W (6.25A) from a different 12v rail probably.

Could try using 1 of the other 6-pin plugs in case all of the above is sharing the same 12v rail. Does the PSU manual say if the 6-pin plugs go off the same 12v rail?

FYI don't use the adapters (4-pin to 6-pin) that came with the card if your PSU has the plugs already. If you use the adapters then the power will be coming all from the same 12v rail.

 

[Bakurei]

Plus I don't think insufficient PSU would manifest in bad performance. Reeboting and sudden shut downs would be more probable.

 

[No Limit]

Your video card probably has 2 power connections on it. Hook up one to the 20A rail and the other to the 18A rail. This will give you a combined output of 38A on the video card.

 

[CowPunk]

Your video card probably has 2 power connections on it. Hook up one to the 20A rail and the other to the 18A rail. This will give you a combined output of 38A on the video card.

This is kind of a dumb question, but what do you mean by "rail"?

 

[Stigmata]

Basically it's a second "route" for the power to flow through. If all the PSU's power went through one rail, it would be an incredible load and would put a ton of stress on the hardware, especially when your power consumption jumps around a lot (seen with gaming, as the GPU quickly clocks itself up and down when you start and quit a game). Splitting the power between multiple rails means that the PSU is far less likely to fail when power consumption changes rapidly.

I... think, anyway. I might be rusty on this

 

[No Limit]

For the most part these power supplies really only have one "rail". In that there is only one 12V supply. But that 12V is split out with individual current protections so that a single cable coming from the PSU doesn't exceed 18A in your case. Each one of these individual cables is what they call a rail which I think is a bit misleading.

The issue is not really with the load through each rail when everything is running fine (once your GPU is connected to 2 rails it combines both rails in parallel which leaves the voltage the same but adds the current together). The main reason they did this is safety. If something goes wrong and you have 40 amps flowing through a single cable that could very well start a fire. But this obviously can provide issues with video cards that require a huge amount of 12V power. Pretty soon we will probably see 3 connectors for the 12V rail on these cards.