On Sat, 2008-02-09 at 12:52 -0500, James Knott wrote:
Tom Patton wrote:
On Thu, 2008-02-07 at 10:13 +0100, Per Jessen wrote:
Randall R Schulz wrote:
Offhand, I don't know how the efficiency of today's power supplies varies with the percentage of their rated output they're producing. In other words, does a higher-capacity PSU consume more mains power for a given level of consumption on its output side? If so, you wouldn't want to have such a large PSU, since that would be wasteful.
I haven't looked at switchmode technology for quite some time, but I would expect a fairly fixed efficiency in the 80-90% range, quite probably more. There will be a minimum consumption required in order to achieve optimal operation, but otherwise I think the output power will be e.g. 80% of the input power, and the rest is turned into heat.
or to say it another way...(at 80% efficiency) a 150 watt supply or a 500 watt supply should either one pull the same current from the mains, if they alternately supply the same 80 watt load (ie MB)...approximately 100 watts from the mains in each example. It would NOT be wasteful to the environment...(but maybe to your wallet).
Tom in NM
You're forgetting there may be some additional power consumed by the power supply itself. This might be a bit more for a larger supply. Even with no load, all power supplies draw some power.
I was correcting the previous post that seemed to say "the rest would be turned into heat". A 500w supply will not pull 500w if the load is only 100. Without comparing efficiency curves of two specific supplies, it is all speculative at best. BOTH supplies at "standby" load would likely be in a rather poor efficiency zone...but would STILL be just a small percentage of the SMALL load...and thus very close to one another. The previous post seemed also to say that the output current would be 80% of the input current...and that is not the correct way to look at the subject... Tom in NM -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org