motherboard supports how many fans?

Solution
It looks to me, just judging from the pictures, there are 8 fan connections. You can identify a fan connection on a motherboard by looking for these connections http://www.buildcomputers.net/images/cpu-fan-power-connector-and-header.jpg

There are two connections there, CPU Fan and SYS Fan. Heatsink fans should always be in the CPU fan connection. Any other fan can connect to SYS Fan connections.

That motherboard has, from what I see, 8 connections. One or two of those may be CPU fan connections.

Your motherboard seems to have labeled them CHA FAN meaning Chassis Fan or Case Fan.

You'll find one in the top left, 2 next to the RAM DIMMs, one directly below the RESET button, one in the bottom right, one in the middle along the...
From looking at the pictures, I believe I see 5 headers. Looking from the top, as if the board were mounted in the chassis in a typical fashion:

One on the top left, two above the CPU block, one by the reset button, and one bottom left by the thunderbolt header.

The way you check, would be look either at the documentation (usually available on their website, or look at a good sized picture and look for the 4 pin headers.
 
It looks to me, just judging from the pictures, there are 8 fan connections. You can identify a fan connection on a motherboard by looking for these connections http://www.buildcomputers.net/images/cpu-fan-power-connector-and-header.jpg

There are two connections there, CPU Fan and SYS Fan. Heatsink fans should always be in the CPU fan connection. Any other fan can connect to SYS Fan connections.

That motherboard has, from what I see, 8 connections. One or two of those may be CPU fan connections.

Your motherboard seems to have labeled them CHA FAN meaning Chassis Fan or Case Fan.

You'll find one in the top left, 2 next to the RAM DIMMs, one directly below the RESET button, one in the bottom right, one in the middle along the bottom, and 2 right above the PCIe slot.

 
Solution