Happy Hopping wrote:
Regardless, why is the MTBF of these 200 mm fans are so much lower than 140 mm fan? We are talking about 40K hr. vs. 100K hr.
In more detail, consider that MTBF is only a rating
not a measurement. They are calculated. They are not an industrial type of design so MTBF is less important. It could also be that because of the cheap way they are designed that they use the motor motor from smaller fans as the base, then attach the big bling fan to it. By doing so they will put higher stresses on the motor than intended for long life, hence a shorter MTBF being calculated. ...Or maybe because they're just rubbish as Pappnaas suggests.
Don't buy this kind of case if you want silence. They simply aren't aimed at it, regardless of what manufacturer data there is saying that they might be quiet.