yup... tats why some people have two system running at their home...

one is high end for gaming or other purpose that required high-end (high power consumption pc)

and another one is low end pc (maybe pentium 3 or 2 with little device for downloading torrent 24hours or normal purpose)

Note that PFC doesn't really affect the efficiency that much. It's primary intention is to correct the power factor which is important for a variety of reasons although for home users it won't affect your power bill. Indeed IIRC active PFC PSUs are very slightly more inefficient then passive PFC PSUs. If you are a big company though, you may be charged a penalty if you have a poor power factor so it will affect your power bill.

PSU efficiency depends on load & generally speaking, if you use an oversized PSU it will be less efficient at your normal load then a properly sized PSU. So in other words, it's a mistake to buy a 600W PSU if you don't need it.

Note that modern CPUs, Athlon 64s and Core 2s are fairly efficient and also have fairly decent power saving modes. If properly enabled, you will save a fair amount of power under light loads, e.g. surfing, office work etc. Most modern GPUs also have some power saving mode although it tends to be a lot less effective then modern CPUs. The P4 is well known as a very power hungry beast and I would dump any P4 systems if you're worried about power usage

This post has been edited by Nil Einne: Aug 8 2007, 02:35 AM