Multi-Rail Amperage Question

[Nekroze]

Hello, recently my PSU died hard so I'm looking for a new one and decided to upgrade half my PC in the process however i am looking at getting a nice Nvidia GTX 480 but it says it needs a PSU with at least 42amps on the 12V Rail, considering I am going to be loading this computer up to the brim with hardware I want to overshoot that a little bit and still have room for overclocks and or upgrades.

 

Anyway back to the problem at hand. I have brought my choices down to two PSU's and although they are rather similar their technology is different enough to confound me a little bit at the very least.

 

I am looking at CoolerMaster Silent Pro Gold 1000W and the Enermax Revolution85+ SLI 1250W (looking to 1250W because the 1000W is not much cheaper) both are very nice PSU's and i have no problem with either however i am rather sure in my belief that the CoolerMaster will run the 480 and more as it has a single 12V rail pumping 98Amps, more then enough. However the Enermax on the other hand, it has 6 12V rails all pumping 30Amps and although its overall amperage is rated at 104Amps on combining the rails will it run the 480 Perfectly.

 

Would I be correct in assuming that if say the 480 had two PCI-E power connectors like the earlier 295 had on the Enermax it would still get its 42 required amps (or a max of about 60amps due to the two connectors) but if it has one connector it would not give enough amperage where the CoolerMaster would.

 

Thanks for your time guys, and I am very sorry for probably making a simple matter far more complicated then it need be its just i dont quite understand it perfectly.

 

Thanks in advance for the help,

Nekroze

[ir_cow]

that's alot of amps, last i checked the 480 only using like 200watts so a 1kw psu may be overkill unless are looking for SLi. anyone what to give the exact power requirements because 42amps is really high i think.

 

what is your rig?

 

 

 

edit: the GTX 480 using 250max on load. took a bit to find. also i always liked single rail better but if you get a good PSU it doesn't have much effect.

Edited August 4, 2010 by hornybluecow

[Drdeath]

1 rail vs 2 rails have different theories. Both are very high quality PSU's and you will not go wrong with either but..... Take a look at the Corsair HX1000 PSU. It is one of the better ones out and got an excellent rating. I saw some reviews test it out 90%+ efficiency at 100% load. The Corsair HX1000 is down to $229 and I feel one of the better bang for the buck. I believe it has multi rails. I own it and it is quiet as a kitten sleeping....... or awake and my overclock and Vdroop is great.......

[Nekroze]

Thanks guys, I know the 1k watts is more then enough but my last one was a 700W and I believe its died from pushing its wattage or some such.

 

its mainly to make sure i can get everything i want snugly and room for more.

 

I got an i7 Rig and when i get the 480 im going to use my old 295 for physX dedicated so thats a bit of power usage right there and considering im watercooling all three of those and the mobo (latter my RAM aswell) and overclocking them to the max its using a fair amount of power, which is why i was also looking at the Enermax psu over the other for higher effeciency rating (on par with the HX1000 i think) and i was looking at the HX1000 but the Enermax was not much more and more wattage but initially it still had the lower Amperage over multiple rails.

 

all considering if i can spring the slight extra for the Enermax over the Corshair then i might as well, the six rails are kind of nice just so long as i can be told by someone who really knows that it WILL run my graphics cards and give the amperage for the 480.

 

Thanks for the good replies guys, very helpful.

[paulktreg]

You'll be taking approximately 500W with a GTX 480 and GTX 295 for PhysX so any of the power supplies touted so far would be more than adequate. You could even go SLI in the future without the PhysX card (can't see it being of benefit in an SLI configuration, but could be wrong?).

 

I personally prefer single 12V rail units but 100A plus is perhaps getting a little silly when you consider the current limit may not kick in until 120~150A! That's a lot of amps should things go wrong.

 

The Enermax as six 12V rails so the only thing I'd say, if you are set on buying it, is to try and make sure each PCI-E plug is on a seperate rail just to spread the load around a little. Apart from that I'm sure it's a great power supply.

 

I'd also like to suggest the Corsair AX1200, it performed very well but there seems to be limited availability at the moment.

[Nekroze]

Ok so I'm settled on the Enermax at the moment, but from that lack of comments on its lower amps per rail am i to assume that the amps mean little anyway or that everyone is just thinking about the watts and doesn't care so much or know about the amps usage in this case.

 

I know everything would run perfect and well above with that wattage and that's cool and not really what i am asking about though its the amperage that is in question. So from the advice here i am to assume that the amperage counts don't really matter? or is it that i shouldn't care about them for some reason that no one seems to be able to voice.

 

I'm sorry that I've gotten myself so confused with this there just doesn't seem to be an answer around.

 

Thanks.

[paulktreg]

Ok so I'm settled on the Enermax at the moment, but from that lack of comments on its lower amps per rail am i to assume that the amps mean little anyway or that everyone is just thinking about the watts and doesn't care so much or know about the amps usage in this case.

 

I know everything would run perfect and well above with that wattage and that's cool and not really what i am asking about though its the amperage that is in question. So from the advice here i am to assume that the amperage counts don't really matter? or is it that i shouldn't care about them for some reason that no one seems to be able to voice.

 

I'm sorry that I've gotten myself so confused with this there just doesn't seem to be an answer around.

 

Thanks.

 

Amps are very important and often quoted with regards to graphics cards.

 

The Enermax as 30A maximum available on each 12V rail right? Maximum is the important word here because if you pulled 30A from all six 12V rails that would be 2160W! You have to look at combined wattages as well and for the Enermax it's 1248W or 104A ( and not 180A) from all the 12V rails added together.

 

I see the Enermax as a total of eight 6+2-pin PCI-E connectors on four cables, one captive and three modular. The Enermax will be wired along the lines of 12V1 and 12V2 for motherboard, CPU and peripherals and 12V3, 12V4, 12V5 and 12V6 devoted to PCI-E power so that each PCI-E cable and hence two 6+2-pin PCI-E connectors gets its own 12V rail. This is more than enough to power any graphics card available at the moment. I know the 6-pin PCI-E connector is rated at 75W or a little over 6A so the 8 pin PCI-E connector is probably no more than 10A which means in theory the most that should be taken from any 12V rail is approximately 16A.

 

Hope that helps?

[Nekroze]

Thank you very much Paulktreg, that's pretty much exactly what i was looking for.

I guess this case is closed then now.

 

Thanks all and have a good one!

Nekroze