$8100 is extremely expensive for a gaming machine. Not questioning whether you can afford it, but rather saying that you can get just about the best gaming experience possible right now for a third as much money or less. Prebuilt manufacturers make their money by upselling you on every little thing along the way as a "recommended upgrade" and by the time you're done you have a 6950X and 4 Titans with 64GB of memory, which in the end will give you an inferior experience to a well clocked 6700k and a single card (or 2-way SLI if your games of choice support it well). The components they push at that price are often better suited to an editing/rendering/developing focused workstation and don't improve gaming performance in any meaningful way. That's not to say that prebuilt computers don't have their place or tell you how to spend your money. Rather I'm just saying evaluate whether the parts, looks, and saved time of having someone else build the machine are worth it to you.
Could you link the build you had in mind? Or if they don't make that easy at least list the components? Also is your intended purpose for this to be mainly a gaming machine or do you do other demanding things with it that require more cores/RAM etc?