electricty

[mickeylee]

how much electrcity does a PC use e.g if left on overnight downloading

[Everhelpful]

Minimal,hardly worth bothering about.

[Buenchico]

According to this Canadian university website, the maximum power consumption of a PC and monitor can usually be regarded as around 175W. That means that 8 hours use will use 1.4kWh of electricity. (Roughly 15p worth):
http://windows.uwaterloo.ca/Hardware/PC_Power_ Consumption.asp

However, those figures assume that the PC is working 'flat out' (with almost constant drive activity) and that the monitor is left switched on (which isn't necessary for overnight downloading). In reality, you'd probably only use about a third of that amount (i.e. about 5p worth).

Chris

[doink]

Why is it common to see even a base, enrty level pc with a p.s.u of 400w?

[Buenchico]

For Doink: I don't claim to be an expert on the power consumption of PC's (which is why I used figures derived from an apparently reputable source, i.e. a university website). However, I suspect that the answer to your question involves some or all of these factors:

1. 'Power' is something which can be assessed in various ways. For example,anyone who knows anything about hi-fi equipment will know that some manufacturers will claim that their amplifiers can produce, say, 30W. They omit to mention that this is 'peak-to-peak', rather than 'rms'. It's possible that PSU manufacturers could use similar ways of 'being generous' with their assessment of the power output of their products.

2. The PSU for a PC has to have 'spare capacity' to power peripherals connected via USB ports. So, unless the maximum power is being drawn through those ports, the actual power consumption of the PC will be lower.

3. Good PC design should ensure that the PSU is rated well above the actual power consumption of the PC (and USB peripherals). This is because any PSU running at its maximum capacity won't fail but it will get very hot (which can mean very bad news for some of the components).

As I've said, I'm not an expert but those are the factors which come to mind when considering your question.

Chris