I'm not surprised that this doesn't change the CPU temp.

The important heat-exchange from the CPU is usually managed by a heatsink and a radial fan, with the grille of the casing designed as fan inlet/outlet.

Blowing/sucking additional air at the inlets doesn't affect the cooling surface of the heatsink, it just blows at the radial fan.

This may make sense if there's a weakness of the radial fan (that heat is building up at the heatsink which the original fan cannot remove).

But it's much more likely that the heat is not distributed well away from the CPU, either to the heatsink (thermal paste) or by the heatsink (weak heatsink design/material).

I'd look into ways to replace the radial fan or the thermal paste