Concerns about going 6870 crossfire

Its time to add the second 6870 for crossfire but I'm having a few concerns;

I am wanting to add a second 6870 to my rig and have a couple of concerns. First of all my motherboard, MSI 890gxm-g65 is a micro atx board and the pci-e slots allow for two dual slot cards but they are going to be right next to each other and where the secondary card will extend out I'm wondering if the power cables such as hdd led, reset, etc will be crushed by the graphics card. My instinct tell me it will work, but has anyone ever run a setup like this on the board im using or a similar micro atx board? Also was if I would benefit from getting a non-reference design card (for the main card) since it will be smothered by the second card or am I better off sticking with the heat being piped out the back of the case? currently I have a reference design XFX 6870. So If someone could share some thoughts or advice as to which way to approach this situation I would greatly appreciate it.. also any recommendations for what 6870 to get as a secondary (or primary) to be paired with my existing reference design one. I'm looking to purchase it off newegg or wherever has the best deal ASAP thanks. My rig is in my signature