Confusion about 12v rails

[Delta]

HI, Great Site you have Jonny! Excellent reviews! Even with all the reviews, I'm still lost in trying to pick out a power suppliy for my new build.

My new to be system:
e6700 ( wanting to overclock it )
p5w dh deluxe
2gb corsair 6400c4
evga 7900 gto ( maybe planning to go sli)
2x WD 250 gb drives ( may want another drive later )
4x 120mm fans

What i am confused about is,DO I need a PSU with more than one 12v rail.
EG: Zippy G1-600w (sli). The zippy has only one 12v rail. Does running 2 GPU's in sli require two 12v rails.

On the 7900 GTO box it says to use a +12volt current rating of 22 amps! If i get another GPU would i need somthing rated at 44 amps?

I am totally confused here! IS there a guide somewhere i can read about on how to choose a psu.

Thanks!

[dBTelos]

Look at the Corsair HX520W, Delta. Here is the best price I could find on it:

http://www.zipzoomfly.com/jsp/ProductDetail.jsp?ProductCode=373100&prodlist=froogle
Corsair HX520W w/ SLi

[Oklahoma Wolf]

EG: Zippy G1-600w (sli). The zippy has only one 12v rail. Does running 2 GPU's in sli require two 12v rails.

Not with that monster... Zippy's not kidding when they say it can do 40A@12v ;)

The recommendation of 22A is meant to include the entire system... you could probably run two 7900's off a 500W Enhance/Silverstone dual 12v unit without issues. The Zippy won't even flinch.

[Super Nade]

The Zippy won't even flinch.

We will find out next week, right Jonny? ;)

[jonnyGURU]

Huh? What? Oh... Yeah. w/ luck. ;)

[Delta]

That HX520 is nice, and modular! would the HX620 be overkill?

But I still am a little confused on why PSU need more that one 12v rail ( i sound like a total nub here).

[jonnyGURU]

That HX520 is nice, and modular! would the HX620 be overkill?

But I still am a little confused on why PSU need more that one 12v rail ( i sound like a total nub here).

By separating the 12V rail into separate circuits, or rails, you isolate EMI noise from one component to another and provide protection from some components if one one another rail were to short out.

[dBTelos]

Yea, the HX620W would be overkill.

[Delta]

Hey, THanks! I will look into gettin the Corsair HX520W. Love the way the modular cables can clean up the look of a case!

Thanks again!

[dBTelos]

Np. Modular connections is great to have :)

[Delta]

I looked into getting the Corsair HX520W, it is $135 here in Canada. The store is NCIX and is 10 min drive. So I can pick them up with out shipping. I also see the Zippy GSM-6600P (G1) 600W, was reviewed a few days ago, its only $150. Is the Zippy the one to go for another $15. The Corsair HX620W is $189 !

Not sure what I should get now! any help? .. I see the Zippy has better regulation, but a smaller fan. 600watts for another $15 !.

[Oklahoma Wolf]

NCIX only has two 600W Zippys in stock, however that would be the one I'd go for. However, if you like the idea of silence or modularity, the Zippy isn't so much better in build quality I'd try to talk you out of the Corsair.

[jonnyGURU]

The Zippy has better reg, but the Corsair is more efficient and quiter and modular. There's no side by side comparison.

[davidhammock200]

I would go with the Corsair, however either will be fine. ;)

[Bbq]

Woah, you live near ncix? That's either vancouver or burnaby! Or i think Langley.

I live about 15 minutes away from ncix richmond.

[Delta]

Thanks for the input! I never knew finding the right PSU would be so hard :). I'm going to try and get the Zippy, if they still have stock. If not ill grab the the Corsair. ITs time to finish this build.

Oh yeah, The Langley store is the one I live 10 mins away.

Thanks again!