Just don’t wait too long before getting the second one. 
If we are talking about cycles rendering, did you have the gpu’s set up correctly… i have two gtx580s in one machine at the moment and the GPU side of the rendering take 50% of the time… so a 1 minute gpu render time takes 30 seconds now… just remember that the CPU has a preprocessing time which is not sped up.
i am think of getting 2 i7 3930k and i am told thay will work but i am not 100%
i made this list https://www.pccasegear.com/index.php?main_page=wish_lists_search&action=wish_lists_search&otherwishlist=jessered566%40gmail.com
mid is the one i want if i can get it also any one know where i could get gtx 580s from cos thay seem to be better than the titan by about 30% (i know people with them and thay used cycles)
uh, if you are looking for dual cpu motherboards, you will need to go to a xeon processor, not the standard core i7 range as they will not compatible… the only one at pccg is http://www.pccasegear.com/index.php?main_page=product_info&cPath=187_346_1298&products_id=20322 which wil work, but the price is quite high at pccg for xeons…
otherwise check out here for more xeon 2011 socket cpus – http://www.techbuy.com.au/searchcat/CPU_INTEL_XEON_(LGA2011).asp
@rontarrant Thanks for the tip.
The only shipping Haswell dual-Xeon systems I’m finding lately are E3 or E5 based. Leaks indicate that 15 core Haswell E7 chips will ship late 2013 but it’s unclear to me if E7 workstations exist. Leaks indicate Enthusiast grade Haswell Core i7 chips won’t ship until late 2014 in 6 or 8 core models.
For those debating Ivy-Bridge vs Haswell CPU rendering, VR-Zone tested Blender 2.67a Cycles rendering (unknown .blend) and found Haswell to have a 13.8% performance advantage. Results can be found here.
HOLY DAM ordering a new custom pc is a big hassle… it reminds me of the beach and the swell of the waves where everyone seems to be in sink and tells me the same things but then the swell gos out and everything everyone told me is wrong and so on so forth so now i need to rebuild it from the ground up for the 5th time i mean i wanted to have this thing 2 weeks ago -_-
but the point is only xeons will work as a duel cpu and unless you want to pay a LOT 1 i7 3970x is just as good as 2 xeons