No, you don't need remove the mobo, just put your PC with the HAF 922 looking to the sky, remove your current cooler, clean the processor, apply the new thermal paste and install your new V8.
I have a Cooler Master HAF 922 and I installed a Cooler Master V8 and you have to remove the mother board. The cut out in the mother board tray is not made of Socket 1366 or 1156 boards. I'm not kidding, you WILL have to remove your motherboard unless you have some AMD or older intel processor.
On a different note, I saw a youtube video about a guy modding his CPU cutout so that it works with 1366 cpu cooler. It looked pretty simple.