Hope this helps:
Below is a comprehensive list of what was needed to get SLI running on a non SLI mainboard. Nvidia has moved away from this technology but I still enjoy it and use it. Per the author of this software, Ember, it will enable different specification Nvidia cards run in SLI and even non SLI mainboards to support SLI.
This instruction is targeted at using differentsliauto to enable SLI on a non SLI motherboard but it captures the hardware id as part of the patch so it should enable SLI with two different specification cards. I make no reference to what cards will work together or what card spec is needed to enable that feature.
Notes: Tested on a Lenovo D30 Dual CPU mainboard rev.2.0 with 128gb ddr3 1866mhz registered ECC memory, two Nvidia GTX 690 GPU's and two Intel E5-2697v2 CPU's to enable multi CPU / GPU and quad SLI support without an Nvidia approved SLI motherboard. SLI did not work on this motherboard prior to this instruction without Quadro cards installed per Lenovo and Nvidia very vague specification. No further testing was done as this procedure must be totally redone to change video cards even when replacing a bad card for the same exact specific card, If you change to a different card it will have a different hardware id and you will need to undo step 11 and redo this instruction steps 3-11 as the patched driver will no longer load.
1. Go to the internet and search for NVidia driver (364.51) or previous for your version of windows. I use windows 10. I used NVidia version 364.51 driver because it works well with the latest build of windows 10 as of 7/25/21 and differentsliauto 1.4 Readme document spells out this driver. I have not seen a significant difference or major advantage to using newer Nvidia drivers for any of my cards.
2. Download differentsliauto 1.4 version. See:
https://www.philscomputerlab.com/sli-on-chinese-x58-and-x79-motherboards.html . All original links to this software appear dead.
3. Use 7Zip or WinRAR or equivalent. Unpack differentsliauto 1.4 to a folder of your choice (c:\junk for example).
4. Make sure you have your video cards all installed the way you like and working properly with the SLI bridge present before installing the NVidia drivers as they cannot be changed again past this point.
5. Install NVidia drivers. Once the official drivers are installed with no errors and the installer has finished, reboot.
6. Find the nvlddmkm.sys driver c:/windows/system 32/ and copy/paste into the same folder you unpacked differentsliauto 1.4 to, disable user account control (UAC) and then patch the nvlddmkm.sys driver using differentsliauto.exe, elevated as an administrator.
7. Run the 'Install.cmd' file from an elevated administrator prompt and it should say 'success!' in green text at the bottom of the window if there were no errors and tell you to reboot. Windows test signing is turned on automatically, if not windows test signing must be turned on then reboot your computer in safe mode.
8. In safe mode, overwrite the patched nvlddmkm.sys file from the differentsliauto 1.4 folder into c:/windows/system 32/drivers
9. Reboot to windows normally, windows test mode signing should remain on and the patched driver will install. Test signing must always remain on as the patched driver is not part of the original NVidia software or drivers. This situation was not corrected during this instruction or testing but does not appear to pose a problem.
10. After reboot go to your NVidia control panel and activate SLI. It is necessary to end task on several apps in task manager before you can enable SLI in Nvidia control panel. Turn back on UAC if you wish and enjoy!
11. Recommendation to capture your hardware id's for each video card from device manager and enable Block Driver installations in Windows for that particular device installation for specific device id in computer configuration to stop unwanted windows 10 driver updates and overrides. See:
https://www.google.com/amp/s/www.ghacks.net/2017/06/03/stop-windows-from-installing-drivers-for-specific-devices/?amp . I also turn off windows updates. See:
https://www.windowscentral.com/how-stop-updates-installing-automatically-windows-10?amp .
Recommendation to use a backup program such as Ghost or Macrium to make a backup of your hard drive after completing the SLI enable feature in this instruction. A backup could be useful throughout this instruction or at each step as well.
Thank you to the writer of this program Ember- differentsliauto 1.4. Thanks to all that made this possible and thanks to those that have kept this software alive on the web.
