On Thu, 22 Feb 2007 09:42:16 -0500, "Mike T."
<noway@nohow.not> wrote:

>
>"Tomaz Cedilnik" <tcedilnik@ntlworld.no.spam.please.com> wrote in message
>news:MlgDh.11059$fa.4855@newsfe1-win.ntli.net...
>> I'm a bit confused. Looking on dabs.co.uk they cost anything between 15
>> and 150 pounds (ok, the top end are those that output 700+, but even
>> exactly 500 can cost anything between 20 and 110 pounds).
>>
>> Seems there is much more to a PSU that the wattage... What do I need to
>> look for in a PSU so it will work with my machine? I've got an Athlon XP
>> 2000+ (1.67 GHz).
>>
>> About wattage - it only draws as much power from mains as needed
>> considering the components that have to be powered at that moment, doesn't
>> it?
>> How do I find out what wattage I need?
>>
>> Tom
>
>There are various wattage calculators online. But any Athlon XP system
>should be happy with less than 400W.

Beware that with current generation PSU that can sometimes
be backwards, that if the Athlon XP based system draws 5V
current for the CPU vcore supply, it will be more cost
effective to buy an older generation PSU because it will
need a higher wattage current gen. PSU to get a high 3V+5V
rating as some needed.



In looking for a power supply, name
>brand is most important, but also make sure it has the right connectors for
>your mainboard. For example, an Athlon XP system probably has a 20-pin
>power connector. SOME newer power supplies have a 24 pin power connector.
>Most are "20 + 4" (modular connector, 4 pins slide off if not needed), so
>those would work, regardless. Looking at dabs in particular, the only
>decent brands they carry are tagan and enermax. I'd recommend tagan, and
>something around ~400W. -Dave
>
>BTW, be careful using the wattage calculators. They are good at adding up
>watts your system will probably use. But your power supply should only be
>outputing a percentage of maximum rated wattage at any given moment.
>Example: online calculator says your system uses 150W. That does NOT mean
>you buy a 150W power supply. Not only would your system run unstable, but
>the power supply would fail quickly, as it is running near maximum output,
>constantly. More realistic would be a 450W supply, so that the system will
>draw a maximum of about 33% of what the power supply can handle. But I've
>had systems much more powerful than yours running off 380W! Name brand
>helps. Many no-name 600W power supplies wouldn't perform as well as a good
>380W supply.
>


A max of 33% is somewhat overkill, generally if the PSU's
most heavily loaded rail is under 75% utilized you're ok...
providing the PSU was accurately rated.