Any physical dismantling or modifications to the product will void its warranty.
If you have space in your case to accommodate a 2 slot graphics card, I'd suggest replacing your 6850 with something a lot more capable like a 7850 1GB. Your current card is a slim design meant to fit in only one slot (usually a 6850 is 2 slot), which has a great impact on how it is able to cool itself. Furthermore it came from Afox which is largely unheard of (at least for me)
Get something like this:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814202004
It's great value for only $170, and even comes with the new Bioshock Infinite and Tomb Raider games for free.
At the very least it is a 2 slot card with dual fans, newer and more powerful than...