Probably not what you'd want to hear, but WX3100 and WX5100 aren't the best to buy for Blender work. Bear in mind that Blender is heavily consumer-grade hardware biased, I have personally not seen any improvement between 1080Ti, Frontier Edition and WX9100 in terms of consumer vs professional cards. I will add though that AMD hardware will not lock or stutter your screen while rendering, whereas the 1080Ti, while admirably fast, ends up killing multi-tasking because of screen stutter. Even on consumer hardware (i.e. RX series) you can render while watching a stutter-free YouTube video or just keep on modelling.
You're actually far better off just getting a decent PSU for at least one of the workstations and getting ONE hefty card, I can almost guarantee that you'll be able to do more with it because 1) 2x WX5100 + 2x Quadro 2000 will not match the render speed of a single Frontier Edition in Gaming mode(if working in Cycles, no difference between Pro and Gaming in Radeon ProRender); 2) you WILL need the massive on-board storage, or HBCC at least, and a bit more RAM.
wimpzilla is correct, you will get PSU throttle, maybe even shutdowns and system instability because of under-supplied PSU, that is really important. An EVGA 850W PSU is about £100, worth saving your equipment and work for such a low price, considering the professional environment.
I do for a living what you're getting into, with Blender and GPU rendering, if you have any questions whatsoever, either ask here or you can find me on AMD's Red Team discord, which is easier to deal with: https://discord.gg/qb7mHwV