Buying new PC & selling old one?

[Hingea]

Hi

I'm looking to replace my desktop with a laptop and external graphics card. However I quite recently built my current PC (within the last year) so it's still got some value to it - however some of the parts from it were gifted to me, so I will more than likely profit from selling it. Does this mean I'm going to pay tax on it? I've had a look at this income tax calculator but I'm not sure if that's right or not so was hoping someone here can explain it to me.

Thank you!