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Installing new PSU - Do not understand rails?

  • Power Supplies
  • Components
Last response: in Components
October 28, 2012 7:41:38 AM

Hi all,

Just a quick and hopefully simple question. My current PSU died and so I have ordered a new one. I am ready to install the new PSU, however, I am very confused about rails.

Before I begin I will quickly list my specs:

ATI 5870 1gb
Intel E8500 @3.16ghz
1tb hdd
1 x DVD/rw

So here is my problem. My current broken 700w PSU has 2x 12v rails, at 22a each. However, my new 800w PSU has 4x 12v rails rated at 32a each.

I am stuck because i do not fully understand how rails work, and do not know how to make sure when I install my new PSU, I am not accidentally putting the whole pc on 1 single rail and blowing it up!

So when installing my new PSU, how do I identify which wires are powered by each of the 4 rails? And how do I make sure my psu is always supplying my graphics card, CPU, and motherboard with enough power?

I am sorry for such a noob question, but it is quite confusing and I don't want to break my pc.

Kind regards,


More about : installing psu understand rails

October 28, 2012 7:47:00 AM

Which power supply is it?

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October 28, 2012 8:20:33 AM

Thanks for the link mate, it's a good read!
October 28, 2012 5:12:28 PM

Link didn't work.

4 separate 32A rails would be rare. Most 800w PSU have a single 60A+ rail or two 30A+ rails. My guess is you have 2 32A rails with four cable runs.

The only think that is going to come close to maxing out a rail is going to be a hungry video card. SO just make sure you don't put two video cards on the same 32A rail and you'll be fine.

The rest of a system is not that power hungry, so it won't really matter unless you have like 12 hard drives.