DescentBB

I must be stupid.

Correct me if im wrong - but i have always been under the impression that Case Fan Sizes (120mm for example) were based on the actual "Hole" where the air passes through.

I ran into an issue with a PC build for my brother.. We purchased a Thermaltake V6 BlacX case:
http://www.newegg.com/Product/Product.a ... ltake%20v6

It features a 200mm exhaust fan out the top.

The case is Black with Red Accents. He also purchased an Asus Crosshair IV motherboard, also Black with Red Accents:
http://www.newegg.com/Product/Product.a ... -_-Product

It was only natural we replaced the Blue 200mm fan with a red one.

We purchased a 200mm coolermaster fan: http://www.newegg.com/Product/Product.a ... -_-Product

Only to find it would't fit! It was too big for the case!

Coolermaster markets this fan as a 200mm, and Thermaltake markets their fan as a 200mm but there is a distinct difference in size.
One is not correct. The Coolermaster opening is 200mm, the thermaltakes is about 170mm.

I got a response from TT saying the measurement is from one mounting hole to another, measuring across the center of the fan.

your thoughts?

generally, its mounting hole to mounting hole for fans... but taking the HWD measurements never hurt.

Not all fan housings are square.

Thats interesting. Either way, someone got it Wrong. Coolermaster or Thermaltake. And both are very reputable brands.

The first picture is the top of the Thermaltake V6 BlacX case, showing off the 200mm case fan.

The second picture shows the Coolermaster 200mm fan, and as you can see, it overlaps all edges of the case.

Someone got it wrong in listing it as a 200mm fan.
Thing is, I have a 120mm fan from Thermaltake, Coolermaster, and Antec. All of them are the same size. Same mounting points and same air-flow area. But the difference between the TT 200 and the CM is distinct.