Power Supply Questions...

Yes you can replace your old 450w power supply with a higher one but it will not consume much more electricity unless you add another peripheral to your computer. for example if your previous PC with a 450w power supply consumes 200w it will still consume 200w even if if you replace it with a 500w power supply. the energy consumption are based on what peripherals (DVD, HDD etc) you have on your pc and the task your processor is doing. the more task your CPU is processing the more energy it will require. Playing games and multimedia eats much more energy than your regular browsing or typing because it requires more processing power, more processing power more energy requires.

Theoretically it won't consume more energy since computer power supplies are switching power supplies(Better ask the manufacturer to be sure they are switching). Meaning, it adjusts to how much power your computer consumes. Theoretically because there are wasted energy when operating the supply, but the difference is negligible.

yes you can replace the power supply with a bigger one, yes you will consume more electricity.

I am so sorry my dear, I am not an authority when it comes to questions of that sort. All I know is that the higher the wattage the higher the consumption and of course the higher bill you've got to face. I just wish somebody here is more knowledgeable so that you could be helped. I wish you luck!

If you replace your power supply it will increase electriciy consumption. But it will not a much difference. If you use UPS it will cause problem if it has not support for your new power supply.