I'm looking for a low power (150W) ATX PSU for a project of mine but I can't seem to find one.

Any ideas where I'd be able to get something like that?

Also, if I was to get a 350W PSU to use on my router machine and turn it on would it be using 350W all the time or does the power usage (i.e. what comes out of the mains supply) change depending on demand on the PSU?

Basically, if I bought a 350W PSU and put only 150W of demand on it would it use electricity at 150W or 350W? (I'm thinking in terms of money saving stuff.)

Assuming 100% efficiency, 150W

350W is the max that it draws (again assuming 100% efficient, otherwise it's probably a bit under 400W from the wall), not a constant

thought of one of these?:

http://www.mini-itx.com/store/?c=10

I use something in an ooollllddddd shuttle box because the original ps died. These are silent (you need an external brick) and can fit mostly anywhere.

Didge.

As Fin says, that is the maximum rating (plus inefficiencies).

Look for an 80+ Gold PSU, which provide over 87% efficiency under load - it is diabolical how bad some PSUs are!

http://en.wikipedia.org/wiki/80_PLUS