One of the most annoying things about SolidWorks is the none existent support for Geforce cards,
But there is a workaround for this and this video details how to get around the issue and get realview working.
1.) Open up the registry editor (Start Button - Run... - "Regedit")
2.) Navigate to "HKEY_CURRENT_USER\Software\SolidWorks\SOLIDWORKS 2015\Performance\Graphics\Hardware\Current"
3.) On the right side double click on "Renderer"
4.) copy (ctrl+C) the Value
Since I have a GeForce Card mine is "GeForce GTX 960M/PCIe/SSE2".
5.) Navigate to "HKEY_CURRENT_USER\Software\SolidWorks\SOLIDWORKS 2015\Performance\Graphics\Hardware\Gl2Shaders\nv40"
6.) On the left side (the tree view) right click on "R420" and choose "New / Key"
7.) Rename the new key with the copied value (ctrl+V)
8.) Click another Key and back to your newly created to make sure you are editing the right values. The right side should be empty but an entry (Default) whose data is "value not set"
9.) right click on the right side and create "New / DWORD (32-bit) Value"
10.) Rename the DWORD to "Workarounds" and, after that, double click it
11.) Leave the "Base" to "Hexadecimal" and enter 30008 into the field "Value data"
12.) Leave the Registry Editor open and start Solidworks. Create a new part / open an old one and try to enable RealView.
If RealView is still greyed out:
13.) Close Solidworks and go back to the registry editor. Doubleclick the DWORD "Workarounds" and change the "Value data" to 30408 or 40408
14.) Fire up Solidworks and try again to activate Realview (Part or Assembly open)
If RealView is STILL greyed out:
15.) Freakout - I can't help you mate.