freakdaddy64
is vertical mounting a big difference in gpu temps.  im fixing to transfer my rig into a corsair 5000d case and i will have plenty of airflow and thought i might try it.

Not exactly sure how the temps would look like, but i own a 5000D Airflow and it seems to me that the side glass would be close potentially choking that air intake from the fans.
However not all vertical mounting kits are the same, i think some can sit your card back more (towards the motherboard), so those might work.
With normal positioning my card keeps cool perfectly on the other hand, the cool air intake from front fans taken in, plenty of space below the card for it's fans to pick that cool air up too.
I think the best is if you get a kit like mentioned above, test it out with and without and take what you like.
 
Not sure if it matters, but i personally don't like the fact of adding another possible critical connection between my card and the MB, this is mostly why i didn't get a vertical kit or thinking of getting one anytime soon.

You can always try it later if you change your mind, but for what it's worth i think normal position will work great for you in this PC case.