Man, it sounds like they really took you to the cleaners building that rig. Way overpriced! And it also sounds like they are either taking advantage of your limited knowledge, or they are ignorant themselves about a lot of things. Of course Windows 10 Pro x64 will work fine with those cards. And patch? What patch? There is no patch. There were updates to the original build, but it would have worked fine before the updates, and now it will work a little better after the updates.
Also, why did you not buy a single Titan X Pascal if you are only going to render with this rig and not game? You would have had great results, and
NONE of these SLI issues. Slightly less performance than two 1080's yes, but a single Titan X Pascal is nothing to sneeze at. You now have a serious gaming rig that you aren't going to use for gaming? And Doom isn't a demanding game at all to use for testing purposes. I easily get >60FPS on max settings on Doom with a single EVGA 1080 FTW at 4k. Try The Division. I can barely keep frame rates in the 40's low 50's at 4k.
Seriously, I would consider returning that monstrosity and getting someone local (NOT THAT SAME SHOP) to help you build your own rig. I just helped my 12 year old nephew make a build, and it was no problem. It's incredibly easy. You'll spend more time selecting what parts you want than actually putting the rig together.
And what processor do you have? You said "intel 6core i7." There are several. And it matters A LOT which one you have. Is it a new Broadwell-E? Like a i7 6800k or 6850k? Or did they give you a last gen i7 5820K? (a i7 5820k is still a fine processor, but is not new, and you need to know what you are paying for). And what exact RAM? You said "RAM - 24GB (32 GB Soon)," doesn't describe what RAM you have. In other words like "CORSAIR Dominator Platinum DDR4 2666MHz" for example. And what configuration? 24GB? You need a lot of RAM for rendering and they should have told you that, but configurations are typically 8/16/32/64/128GB etc.... Not 24GB?
A week or so of Googling and a little research to educate yourself about components might have save you a lot of hassle. I'm not trying to be mean, I feel bad for you really, but you could have built an outstanding rendering rig yourself with a single Titan X Pascal and a 6 core i7 6800k and saved $1500 if not more.
Your motherboard "Asus Rampage Extreme V" is an Extended ATX board (in other words huge!), and is overkill for what you needed. And it a $500+ motherboard! Did you pick it or did they recommend it? Again if they told you that you needed this board, they screwed you over.
Also, what PSU do you have? This is a
BIG factor when running two cards in SLI. It needs to be a high quality Gold or Platinum certified unit, of a good brand like SeaSonic, or Corsair.
Sorry bro, but you got taken. I'm not up on my Canadian consumer protection laws, but I would go back and demand a refund and give them back that thing.