Hello @jmike thanks for posting and welcome to the Valhalla forums.
I can confirm that SLI or multiple graphic card setups are not supported in Valhalla or most of our games at the moment, so whilst we can offer you some troubleshooting to try and improve your FPS rate, what we can advise you will be limited by this.
Thanks for letting us know you experienced a better performance with the SLI enabled instead of disabled on one of your benchmarks. It may prove useful to tell us a little more about your setup and what other component models you have installed in your PC, whilst you await an answer from another SLI user.