PSU Amperage questions

[Atls]

Heya. Got a quick question:

If I had, say, a 500W power supply with 2 rails, with 18A on each +12V rail, what would the TOTAL amperage be? Do I just add them up, or what?

I need to know if I can power a 5850 and more components. Is it 18A, or 36A, or what? Thanks.

 

[theAnimal]

Total 12V amperage would depend on the PSU and should be listed on the label.

A good quality modern 500W PSU should have somewhere around 40A on the 12V rail(s), and would be fine for a 5850 and single CPU with a few HDD.

 

[fffblackmage]

You cannot simply add the amperage of multiple "rails" to get the total amperage. You have to look at the label. Here's an example:

This PSU can provide 456W on the three 12V rails combined. That's 456W / 12V = 38A.

A decent quality 500W PSU should be able to power a 5850.