Odonil,
You have your answer actually. That's the point of asking the question to you.
USAFRet,
I think one can build a powersupply out of 9v batteries, small step up transformers and resistors if they really desired but with PSU's in abundance for purchase of reliable units, who'd want to waste time doing so?
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I never said no power at all I said without a PSU
Well it
now looks like you're trying to find an alternative power source like biofuel. Considering how a power supply unit has the necessary components to provide stable and reliable power to your PC, there aren't any other material alternatives for this case.