new ryzen pc build for rendering - does it make sense? what gpu?

Hi All
I’m trying to put together a new PC and since i saw the benchmarks on tomshardware ( http://www.tomshardware.com/reviews/amd-ryzen-7-1800x-cpu,4951-9.html ) I kind of set my mind on the ryzen 1800processor.

I already have a GTX790 that i will put in the new build, and i was thinking of buying a 1080Ti alongside for when i need to render

my case scenario is freelance work where i ususally am blocked by the hardware at the end, because it needs to render and i kinda cant work during this time.

so my questions are the following:

i was thinking of going for ryzen in case i need to render SSS or hairs, or just to be able to keep working while i render on 2 gpus. I assume it isnt possible to render on both gpus AND CPU at the same time? can someone confirm this?

all in all i am open to reasonable suggestions, as i am in no way an expert of hardware :slight_smile: