Minimum: This kind of fan in size of 14cm is normally designed for air extraction, and often provided on PC gamers boxes behind or above the box and there I said forget this idea outright :
-In Low position air extraction (facade head down fan inside the case), it is not at all suitable for here, you feel the fan strength tremendously, it makes a noise monstrous scrap and above all it vibrates the casing so the components in the box!
So to sum up, do not buy this product to turn upside down, as this is harmful to the ear than the damage it could cause to electronic components due to excessive vibration in the case.