OT: How many internal IDE drives maximum off of an ATX power supply?

[Lennart Sorensen]

On Thu, Sep 20, 2007 at 04:52:56PM -0400, Madison Kelly wrote:
> Look up the max volt-amps drawn by each drive for the 5vDC and 12vDC 
> rails. Then look at the maximum amps available on each rail (5vDC and 
> 12vDC). I really doubt it, but you may have multiple 12vDC rails which 
> will have their own max draw plus a combined max draw across all rails.
> 
> Lastly, you will need to determine how much amperage draw the rest of 
> your system draws on the 5vDC and 12vDC rails, and make sure those plus 
> the combined draw of your HDDs doesn't exceed the max draw of your PSU.
> 
> Lastly, it is important to realize that switching PSUs have a curve of 
> efficiency. *Generally*, PSUs are most efficient around the 75%-85% 
> range. Most better PSU companies will show you an efficiency graph.
> 
> One thing to understand, that *many* people miss, is that "wattage" on 
> PSUs is often *very* deceptive and often flat out misleading. I've seen 
> 500w cheap PSUs fail long before a well built 350w PSU. Shady PSU makers 
> love to play fast and loose with their wattage by doing things like 
> saying 500w PSU!!! (*max 350w on the 12vDC and 5vDC rails).
> 
> So long answer short; it depends on the quality of your PSU and the max 
> amperage available on the 12vDC rail mainly, with the 5vDC rail being 
> important but much less so.

Cheap power supplies will also give their rating based on running at 25C
internal temperature, while normal operation is more like 40C inside the
power supply.  500W at 25C isn't 500W at 40C for most power supplies.

I buy power supplies from Antec, Enermax, Silverstone, and of course PC
Power & Cooling.  If you want to be sure it never fails, get the PC
Power & Cooling option.  Silverstone is good for quiet media systems,
and Antec and Enermax make good power supplies for the money and are at
least honest about what their power supplies are.

The think included with a $25 case is a piece of scrap metal and should
not be inflicted on your expensive electronics. :)

--
Len Sorensen
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