The HAF Stacker 915
The smaller Mini-ITX case on the HAF Stacker 935 is the 915. There are actually two different 915 cases, but when you get the 935 the 915R is the case that you will get. The 915R and 915F are pretty much the same case, except for a few minor details. The cases themselves have dimensions of 228 x 248 x 578mm / 8.97 x 9.76 x 22.75 in.
The 915R that comes with the case does not have any power buttons or anything like that on the front. This is because it is made for external watercooling or storage. The front is all mesh and has a single 5.25-inch drive bay. The 915R on the other hand does have a power button on the front along with HD audio and dual USB 3.0 ports. Now if you wanted to use those on the 915R the I/O panels are interchangeable between the cases.
The sides of the cases are exactly the same. In the shots below you can see that the 915 is a rather long case. This is so it can stack with the main compartment of the 935. Each side of the case has a large mesh section that can support three 120 mm or two 140 mm fans. These side panels can also support 360 mm or 280 mm radiators. So in total you could fit six 120 mm fans, or four 140mm fans, or dual 360/280 mm radiators! That is awesome for a mini-ITX case!
Both cases support mini-ITX motherboards and have two expansion slots to support a single dual-slot graphics card. The 915R as the name suggest has the power supply mounting on the rear of the unit. Both cases support normal-sized ATX power supplies. The 915F has a 140mm exhaust fan on the back of the case as well as a power connection that has been routed from the front of the case. Because the 915F does not have a power supply mounting on the rear of the case it makes room for larger CPU coolers on your mini-ITX system. There are thumbscrews on each side panel for easy removal.
The top of each 915 has a mesh design to allow air to easily enter and exit the case. The top section of each case can be easily removed to stack the cases and to allows cables from other systems in your stack to be routed between the systems. The bottom of the case also has one large cable routing hole as well as 4 smaller ones to help do the same thing.
Moving inside we can see another difference between the cases. On the left we have the 915R which has a hard drive cage. The 915F on the other hand does not have a hard drive case as that area of the case is made for the power supply. Do not worry though there is still room inside of the case for three hard drives and you can actually take the cages out of the main compartment and install them in the 915F if you like.
The hard drive cage on the 915R has three hard drive trays in it. These trays easily come out and support both 2.5-inch and 3.5-inch hard drives.
While the 915F does not have hard drive cage there is room for hard drives to be mounted on the bottom of the case and vertically along the back wall of the case.