[mdlug] Power supply & hard drive

[Mark Thuemmel]

On 05/21/2011 06:28 PM, Garry Stahl wrote:
> Mark Thuemmel wrote:
>> > I generally buy the cheapest power supply possible, but have been
>> > thinking about energy efficiency lately.  This PS says "energy star"
>> > rated for just a few bucks extra:
>> >   
> I strongly disagree with the cheapest power supply.  You should be the
> best for your money.  Remember nothing is between the power supply and
> the mother board.  A blown PS can take down the whole computer,
> permanently.  I always over rate my PS.  if my board and drives are
> pulling 400 I buy 750.  That means a longer life on the power supply and
> cooler operation.

I'm not an electrical engineer in real life, but here is how I think:

Your total amperage draw from your
cpu/memory/drives/video/motherboard/fans should be about 60% of the
rating of the power supply.

The best efficiency for power consumption and heat is when the power
supply is running at about 50 to 75% of its rating.

Your example of 750 for 400 seems reasonable, if you really draw 400.

Since the poster mentioned he wanted a media desktop (mythbuntu) I
figured one green hard drive, dvd writer, Pentium e8400 cpu with fan, 2
gb RAM, an average video card, and maybe an internal tv tuner card.

I'm guessing that configuration would be using around 250.  The power
supply I linked to was 480.  Both of us were close to 50% of draw of the pc.

I'm afraid I usually over buy too, but generally because 400 watt power
supplies are so cheap.  I'm thinking of paying more attention to the
amperage of the components before buying my next one, and trying
something like an 80% or more efficient 350 watt power supply at around
65% draw to cut energy costs.

I guess in my world, I buy the cheap motherboards and keep computers in
dirty areas with dust and such.  I don't clean the insides as often as
they should be, and the power suppy and cpu fans eat the dust,
literally, and die in a few years.  I don't remember ever having a
motherboard die the same time as a power supply, even when the power
supply over heats when the fan clogs.  When a cheap power supply limits
the life of my motherbaord to 3 years, it's time to get a new
board/cpu/memory anyway.