the mains voltage is not relavent to what you want to do.
Ram video cards and drives run off low voltage coming from the power supply, so can be exchanged.
My parents live in Europe and their desktop computer has power supply that obviously runs on a different voltage than my desktop here in the US. I have some extra RAM and graphics card that I was thinking of bringing and installing into their desktop but now I am not sure if that would work because of the voltage difference. Or perhaps it doesn't matter?
I would appreciate some input. I wouldn't want to bring all that stuff with me for nothing ....