[CentOS] Re: OT: How many watts do I need?

[Peter Arremann]

On Wednesday 02 January 2008, Ugo Bellavance wrote:
> Fajar Priyanto wrote:
> > Is 430Watt enough?
>
> What brand?

And that is the right question. I have an Antec power supply that is rated at 
450W that I used to replace a non name 650W one. The 650W burned out while 
the 450W works just fine. 
The reason is easy. The power supply has different rails. Different rails are 
used for the different voltages (3.3, 5 and 12V). Some high end supplies have 
more than one rail for certain voltages. 
The problem comes in that most cheap manufacturers simply add up the maximum 
allowed for each rail and use that. However, these power ratings are not 
independent. Most power supplies create the 3.3V from the 5V. On the power 
supply you will then see stuff like "Combined maximum for 3.3V and 5V is 25A"

In short, a good 430W power supply will easily deal with what you have 
planned. If it is a cheap one it will probably burn out. 

http://www.playtool.com/pages/psurailhistory/rails.html

Peter.