So i spent a couple hours last night working on getting my two GTX 580's (1.5 GB and 3 GB) to SLI. After a long time of browsing the interwebs i was able to piece together how to do it without modding or using modded drivers. Figured if i had this much trouble there's bound to be at least a few others out there who have the same problem so i thought id post how to make it work. BTW i am using windows 8 x64.
1. The drivers that you want are the 310.70 WHQL.
2. You will also need to download and install CoolBits 2.0
3. Once downloaded uninstall the Nvidia display driver via control panel.
4. Run the executable for the 310.70 drivers
5. Extract Coolbits 2.0 from downloads and run the exe it creates. Click allow when asked for permission to edit registry.
6. Go into regedit.exe
> locate [HKEY_LOCAL_MACHINE\SOFTWARE\NVIDIA Corporation\Global\NvTweak]
> right click on the "CoolBits"=dword:00000003 in right panel and click modify.
> Change the Value to 1A. This allows for overclocking and SLI of different VRAM sizes.
7. Restart your machine and when you log in check in Nvidia control panel and the SLI option should be there.
1. The drivers that you want are the 310.70 WHQL.
2. You will also need to download and install CoolBits 2.0
3. Once downloaded uninstall the Nvidia display driver via control panel.
4. Run the executable for the 310.70 drivers
5. Extract Coolbits 2.0 from downloads and run the exe it creates. Click allow when asked for permission to edit registry.
6. Go into regedit.exe
> locate [HKEY_LOCAL_MACHINE\SOFTWARE\NVIDIA Corporation\Global\NvTweak]
> right click on the "CoolBits"=dword:00000003 in right panel and click modify.
> Change the Value to 1A. This allows for overclocking and SLI of different VRAM sizes.
7. Restart your machine and when you log in check in Nvidia control panel and the SLI option should be there.






