The DRZ400 fan does not fit if you have the Clarke 4.3Ga. tank (tried it) It will rub on the tank and/or on the rad... your choice. I've been running cool due to other mods made, but if I were to use a fan, the KTM will be it. About computer fans... I would not recomend them for many, many reasons. Flow, head loss, vibration, heat, (when at back) dirt. BTW, I never tried one.