Good information to know that 2696 v2 works with the HP z820 which i am a little surprised because i figure hp might not support oem cpu since this cpu is not on their z820 cpu list. I know it also works with Lenovo D30 which i have. I personally prefer the Lenovo D30 (dual socket will work with 2696 v2) and S30 (single socket but doesn't work with 2696 v2) because they both use mostly generic components including psu. I just replaced my parents s30 psu with a drop in from best buy for $40 after the original went out from power surge.This is is very good information to point out, the 9696 v2 is OEM and may not work on all mainstream motherboards/manufacturers, so it is something to watch out for. If you are still choosing to go down this route, I would recommend something like the HP z820, which is a dual socket LGA 2011 motherboard, with this combination, will give you something like this with CPU-z score, and like you said, will provide slightly better performance than a single 1950X TR, as you can see here.
You can also see here, that contrary to what you read on the internet, the 2969 v2 has a single core boost of 3.5GHz, NOT 3.3GHz....
Someone here also mentioned before that 2696 v2 does work with dell T620. I know for sure 2696 v2 doesn't work with intel s2600 MB but does work with asus z9pe MB