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Two vs three 12v rails for PSU?

#1
I'm upgrading my system and am in the process of selecting a new PSU that will adequately take care of my current needs while leaving me some headroom for future upgrades, all at a reasonable price.

One thing that has been confusing me as I look at the available units is how there are now models with three 12v rails as opposed to just two. What I am wondering is if there is any particular advantage to getting a model with three 12v rails over one with only two. I am not building an sli system, nor will I in the future. With going three rails give me more upgradeability in the future? All things being equal, is three better than two?


Here are the two main PSU's I'm looking at:

http://www.newegg.com/Product/Product.asp?Item=N82E16817103457

http://www.newegg.com/Product/Product.asp?Item=N82E16817103939

Here's what my final build will be, I'm not planning on doing any overclocking, just regular work and some game playing. Will either of these two PSUs be enough power? and if not, what wattage should I be shooting at?

Athlon64 3000+
Zalman 7000alcu hsf
Asus A8N5X mobo
2x1gb Corsair XMS pc3200
2xSeagate Barracuda 7200.7 120gb sata (raid0)
xfx geforce 7900gt
Soundblaster Audigy 2 ZS
Antec Sonata


Also, should the A on the 12v rails be the main priority? I mean, if one PSU has 32 at 3.3, 32 at 5, and 18 on the two 12v, is that better or worse by comparison to a PSU with 26 at 3.3, 28 at 5, and 20 on each 12?

Thanks!
 
#2
If you plan on doing SLI 3 rails is best (1 for MB 1 each for the vid cards). Each one will be individually regulated provide clean power sepeartely to each of the big loads.

If you don't plan on SLI or crossfire then 2 rails is as much as you can use.

The Neo is usually Antec's wimpy line. I have seen a lot of people have problems with them. The 3 rails at 16A each is impressive but total power is only 430W. I would avoid that for your current system let alone an upgrade.

The Enermax is better with 18A on each 12V rail but it's wimpy to support crossfire or SLI with top end video cards. If you don't ever plan on dual video cards it is good.

Neither power supply is SLI certified by Nvidia.
 
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#3
Thanks for the reply!

As I stated in my op, I do not plan on going sli now, or in the future, so I guess 2 rails is good enough for me.

Now, I just need to figure which of the these two PSU's to get then, any opinions on the better? or is it mostly splitting hairs?

http://www.newegg.com/Product/Product.asp?Item=N82E16817103929

http://www.newegg.com/Product/Product.asp?Item=N82E16817103457


However, noticed this higher wattage PSU for not much more, but it comes in two versions, can't tell if there is any substantive difference other than fancy fan controls?
Anyhow, would this model trump the previous two choices due to higher wattage?

http://www.newegg.com/Product/Product.asp?Item=N82E16817103931

http://www.newegg.com/Product/Product.asp?Item=N82E16817103933



Thanks!
 
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#4
The more expensive one has more bells and whistles.
-It allows the user to adjust the output voltages manually. Nice feature for an overclocker or massive SLI rig.
-It has a couple of speed controlled fan only connectors so the power supply can adjust case fan speed and noise when the temps are low.

Neat find. I did not know Antec had this new Truecontrol line up.

The cheaper one is as good a supply but without teh added features for $15 cheaper. Either would be a good choice. But then any of the 4 you listed would be good. I'd go for the cheaper Truepower 550W but that's because I under sized my last two power supply buys. :dead:
 

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