Google is your friend. This sort of question is best answered by trying a Google search for the specs of that board instead of opening up a thread. This link was the very first result of a Google search for "ASUS P8H61-M LX" and states that with two DIMMS, it supports up to 16GB, so it must support 8GB modules.
* The maximum 16GB memory capacity can be supported with 8GB or above DIMMs. ASUS will update the memory QVL once the DIMMs are available in the market.
It then goes on to say that the board should also support higher capacity modules. However, if you want 8GB of RAM capacity but only want a single 8GB module rather than two modules, keep in mind that you're sacrificing dual-channel for it. It's not a huge performance boost, but it helps a little.
Also, nitpicking here, but memory module is not a proper noun and shouldn't be capitalized as Memory Module. It's just memory module or module.