That is not supercharging. A computer fan is not designed for compressing air, and it's nowhere near powerful enough to do so. There may be a small increase in performance, but that is just because you overcome the restrictions (increasing airflow) in the inlet manifold
The so called 'electric superchargers' which you can buy on ebay have been mythbusted many times [0]
The so called 'electric superchargers' which you can buy on ebay have been mythbusted many times [0]
[0] https://www.youtube.com/watch?v=cbGWgvJN1_8