It works but reduces the hash to ~14Mh. Even with -x 1(3Mh) on the main card the pc is completely laggy/choppy and unusable.
I have no problem running EWBF with full speed and being able to use the pc.
Is the nexus spmod similarly laggy?

spreadcoin:
default 15Mh http://i.imgur.com/L6umHqs.png
-x 40 14Mh http://i.imgur.com/BVCk3m7.png
-x 20 16Mh http://i.imgur.com/MIbUK7e.png

1080ti @ 1911/5130 and 5152 (identical cards need different mem speed for that timing strap sweetspot I guess).