Just because Monarch says they don't work I wouldn't believe it, if the box says SLI on it then it's been tested and conforms to the SLI standard set by nV. Who knows, when he configured his rig Monarch might have only had 1 BFG in and a buttload of eVGA or got the eVGA's at a tidy discount that they weren't passing along.
I worked in a computer shop and after that I know that they'll come up with all kinds of b.s. to sell a particular product when it suits them.
4690K @ 4.6Ghz
2X4 Gigs G Skill F3-14900CL8-4GBXM
EVGA GTX 760 SLI
Fractal Design Define R5
Dual loop WC
Some other stuff,
Even more stuff,
If the automobile had followed the same development cycle as the computer, a Rolls-Royce would today cost $100, get a million miles per gallon, and explode once a year, killing everyone inside. --Robert X. Cringely, InfoWorld magazine