Installing the mainboard is nothing of the ordinary. Simply use the included mainboard headers and secure the board with the screws supplied. The entire unit is easily reachable, as no part of it is covered by any drives or other parts of the chassis. I have routed the I/O cables down by the lower edge of the board and under the hard drive cage. One could do even better by routing them under the mainboard, but this will do just fine. It is very difficult to route cables and requires a lot of creativity to hide them within the DH series of cases.
Installing the hard drive is easily done by unlocking the plastic part, then sliding it into place. Once the securing mechanism is back in place, the hard drive was actually held in place fairly good, but still allowed for some slight movement. Those installing three drives here may experience some vibration issues. Putting the ODD in place is very similar, just slide it down the bay and push the lock in place. The result is the same, with a good grip, but still allowing a bit of movement. Last but not least, installing the PSU is done by simply using four case screws. As you can see, I have chosen to use the power supply fan to pull air away from the CPU and out the back.
Once everything was connected, you can see, that I have tried to hide unneeded PSU leads under the optical drive bay and the mainboard area is fairly clear. All the fans were connected straight to a Molex connector of the PSU bay.