A couple of PSU questions.

[CaptainNemo]

I am concerned about my electricity bills (or rather the people who pay them are), especially as I often run this computer 24/7...

If you extract 200w from a 550w PSU, will it produce less waste/thermal whatever than extracting 200w from a 300w PSU?

If you keep a PSU very cool (i.e. so cool that the heatsinks are cold to the touch) increase conversion efficiency?

Oh, and the 5V line on my PSU has started dipping below 4.5V and rarely puts out more than 4.6V - is this bad?


"Some mice have two buttons. Macintosh has one. So it's extremely difficult to push the wrong button." - Apple ad. circa 1984.

 

[slvr_phoenix]

Oh, and the 5V line on my PSU has started dipping below 4.5V and rarely puts out more than 4.6V - is this bad?

Very bad.

I am concerned about my electricity bills (or rather the people who pay them are), especially as I often run this computer 24/7...

Then don't run it 24/7. At least be sure to set up your power management well.

If you extract 200w from a 550w PSU, will it produce less waste/thermal whatever than extracting 200w from a 300w PSU?

As far as I know it should produce less heat because the components will be further from their maximum usage.

<A HREF="http://ars.userfriendly.org/cartoons/?id=20031017" target="_new">Then what's your poison of choice?
Soymilk. I was raised on the stuff.
Ah. What's it made of?
Soy.
Is that soy as in soylent green?</A>

 

[CaptainNemo]

How bad is 'very bad' - is it bad enough to result in fried components?

Any ideas on my keep the PSU really cool so it is more efficient hypothesis?

"Some mice have two buttons. Macintosh has one. So it's extremely difficult to push the wrong button." - Apple ad. circa 1984.

 

[slvr_phoenix]

How bad is 'very bad' - is it bad enough to result in fried components?

Fried? Not likely.
Faulty behavior? Definately.

Any ideas on my keep the PSU really cool so it is more efficient hypothesis?

Well I could easily be wrong about this one but if I had to make an educated guess then I'd say no, it wouldn't make it more efficient. The heat generated is a product of inefficiency. Better removal of that heat doesn't make it any more efficient, it just makes it cooler.

<pre><b><font color=red>I've always wondered why people liken the taste of blood to copper.
It tastes much more like iron to me.
<- - - - - -></font color=red></b></pre><p>

 

[Guest]

Typically, a switching FET (PC supplies are based on these)will have a lower saturation drain source resistance at lower temps. Keeping them cooler would allow for a slightly better efficiency, due to less energy being wasted in IR (IR from the formula V=IR) losses. I would say that practically speaking the difference would be so small you will never notice it in your power bill.

 

[slvr_phoenix]

I would say that practically speaking the difference would be so small you will never notice it in your power bill.

That's what I figured too. Yeah, technically lower temps means less resistence which means better efficiency. However the difference in temps has got to be too small to really make a change that anyone could possibly notice.

<pre><b><font color=red>I've always wondered why people liken the taste of blood to copper.
It tastes much more like iron to me.
<- - - - - -></font color=red></b></pre><p>

 

[slvr_phoenix]

CaptainNemo, out of curiosity why do you run your rig 24/7 and what steps (software or hardware) have you made to reduce the power usage?

<pre><b><font color=red>I've always wondered why people liken the taste of blood to copper.
It tastes much more like iron to me.
<- - - - - -></font color=red></b></pre><p>

 

[CaptainNemo]

I often leave it on overnight for P2P reasons (newsgroups - emule etc) or if something needs several hours rendering time.

I don't leave it on unless it is doing something, and I always switch the monitor off (thirsty 21" CRT) when it isn't needed.

I was curious about the PSU efficiency because a single 92mm fan @ medium RPM can cool the whole thing down until the (safe to touch) components are cold to the touch. I have modded my PSU so it runs externally; I have also removed all of the enclosure apart from the base plate (which supports the circuit board) and one side panel (which the transformer is bolted to).

"Some mice have two buttons. Macintosh has one. So it's extremely difficult to push the wrong button." - Apple ad. circa 1984.