Hi, Questions:
did you just recently add a second GPU?
How did you go about it when installing the second GPU?
This is what all ways works for me, If I am going to change or add the GPU setup:
1. Uninstall you graphic drivers.
2. Reboot
3. Run a program like driversweeper and check for any remaining graphic driver files, then clean them with the same tool.
4. Shut down the system.
5. Place 1 GPU in the pci-e slot x16
6. Reboot.
7. Download the latest graphic software and install it.
8. Reboot, check if the GPU is running oké.
9. If it works fine, shut down the system.
10. Install the second GPU (CHECK your manual to see which pci-e slot should be used when running 2 x GPU in SLI/Crossfire.
11. Install the second GPU, PLACE the SLI/ Crossfire bridge and connect both GPU's.
12. Reboot, the graphical drivers should now see the second GPU and enable SLI.
13. Run a test (like 3DMARK Firestrike Extreme) and check if SLI is working now.. because it should.