[mythtv-users] OT: Hardware recommendations or suggestions

Brian Wood beww at beww.org
Wed Jan 16 18:14:47 UTC 2008

John Drescher wrote:
>> Well that knocks one thing off the immediate list to buy then.  Unless of
>> course it is bad.
>> How do you tell the load the PS is pulling?
> I have a KillaWatt meter I bought off newegg.

That will show you only the total AC power draw.

One problem with computer power supplies is that the total wattage is 
given, not how much current for each of the voltage supplies.

It is quite possible to draw too much current from the +12VDC rail and 
still be under the total wattage for the PS, especially if you have 
several PCI cards drawing a lot of 12V.

Unfortunately the only way to know how much current is being drawn from 
a particular voltage source is to break the current path and insert a 
(milli)ammeter. You can do it without breaking the path if you have a 
hall-effect DC current meter, but those are extremely expensive (more 
than several complete computers). AC current meters are cheap, which is 
why the Kill-a-Watt is reasonably priced.

In my experience most power supplies, especially cheap ones, have more 
current capacity than is needed on the 5VCD rail and are marginal on the 
12VDC source.


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