The only way to find out is contact someone HP or the dealer who will configure it for you. The CPU's internal memory controller does in fact only support 8GB of RAM. However, HP may have an external memory controller on the northbridge chipset. If HP does in fact have an external controller for the memory, then the memory access time would be slower, and no point to even use the i7 then.
Also, if you need more responses for memory related questions, try to re-post your query in the memory section of the forum.http://www.tomshardware.com/forum/forum-30-201.html