How to enable SLI, check if SLI is enabled, actually working in your game and what to do if it's not
Since there has been confusion about how to enable SLI, how to check if it works on the system and in individual applications/games, etc. I thought I'd write up a little guide for it, which will hopefully allow everyone to get SLI working on their Alienware laptop and their favorite game.
For SLI to work, you'll require a computer with at least two compatible, SLI capable Nvidia video cards linked with an SLI cable and the latest Nvidia drivers. On some systems, (Hybrid-) SLI/Graphics will also have to be enabled in the BIOS or Integrated Graphics disabled. Owners of select Alienware systems will also have to make sure that they are not in the power saving mode called "Stealth mode" for SLI to work.
I. Check if SLI is enabled and working in your game(s)
The first thing you'll want to do is to check if SLI is enabled properly and running in your 3D Application/Game. To do this, follow the following steps:
1. Make sure you have SLI enabled, by going to the Nvidia control panel by right clicking on the Desktop and slecting NVIDIA Control Panel.
If you don't have the Nvidia control panel installed, you are likely using drivers provided by Windows Update. In this case, skip forward to Section II.A. of this guide to install the latest drivers.
2. In the Nvidia Control Panel, click on Set SLI and PhysX configuration in the Task menu on the left side.
3. Make sure the radial button next to Enable SLI (recommended) is marked. If not, mark it, click Apply and follow the on-screen instructions.
4. When that's in Order, click on Adjust image settings with preview. Make sure Use the advanced 3D image settings is marked. If not, mark it and click Apply.
5. When that's in Order, click on Manage 3D Settings in the task menu on the left.
6. On the right side, look for an entry called SLI Performance Mode. Make sure this is set to NVIDIA recommended.
7. To check whether SLI is working in your game or not, go to the 3D Settings in the horizontal menu bar (not Manage 3D Settings in the task menu!) and make sure Show SLI Visual Indicators has a checkmark next to it. This will enable the SLI visual indicator in 3D Applications like games, which will show up as a green bar on the left side/middle of the screen and SLi written next to it if SLI is working in a 3D Application/game.
8. Close the Nvidia Control Panel.
9. Start the 3D Application/game you wish to check SLI on. If the green SLI visual indicator overlay appears on screen that says SLI, SLI is working in your game and all is good. If no indicator appears, it's not working (unless it's the PhysX indicator that comes with newer PhysX revisions, but that one says PhysX > GPU or PhysX > CPU).
10. If it's not working, try some other games/3D Applications and see if the SLI visual indicator shows up there. If it does, your driver likely doesn't include a proper SLI profile for the game you've tried before yet. In this case, move on to section II. of this guide.
II. Add/Update an SLI Profile for your game
This section describes how to update your Nvidia driver's SLI profile to support your game. There are several ways to do this, one is by updating the drivers to the latest version, another with the latest Nvidia SLI Profile Update, using the nHancer Nvidia profiling Utility or a combination of the aforementioned. These will be described in the folloing subsections.
II.A. Update your Nvidia driver to the latest version
SLI support is provided to games via Nvidia Driver profiles. The newer your game, the more likely it is that there is no profile included in older drivers. Therefore you should update your video card drivers to the latest version.
Warning: Not all Nvidia drivers are fully compatible with all hardware. This is often the case especially with various Notebook video card combinations, especially ones that feature Hybrid SLI. These usually need special drivers to work correctly. These are usually based on older driver versions. Make sure to install the proper drivers for your hardware. If you don't feel comfortable with updating your video card drivers or don't wish to update your driver to the latest version for whatever other reason, skip on to section II.B. and/or II.C. of this guide to get a working SLI profile for your application/game added to your current Nvidia video card driver.
Otherwise, continue with the following steps:
1. Download the latest Nvidia driver for your video card (in case the official Nvidia drivers don't work properly with your video card/system, download the drivers from your hardware manufacturer or give the modified drivers over at LaptopVideo2Go a try).
2. Install the driver.
3. Follow the Instructions from section I. of this guide.
4. If it didn't help, continue with section II.B..
II.B. Nvidia SLI Profile Update
Nvidia has been providing periodical SLI Profile Updates when new games have been released for a while now. These updates add SLI profiles for many newer games to older drivers, which should allow these games to fully utilize SLI.
1. If your new driver doesn't feature a proper SLI profile for the game, you will need to add/Update a SLI profile.
You can Nvidia.com's driver page.
2. Scroll down if needed and click on Nvidia SLI Profile Updates.
3. Check if the game you need SLI support for is mentioned in the Release Highlights of the SLI Update.
4. Download and Install the latest SLI Update.
3. Follow the Instructions from section I. of this guide.
4. If it didn't help, continue with section II.C..
II.C. Create a custom SLI Profile using nHancer
nHancer is an advanced profiling utility for Nvidia video cards. It allows you to tweak many (often hidden) Nvidia driver features which can't be done with the Nvidia control panel on a game-to-game basis, including setting SLI compatibility, getting Anti-Aliasing to work in games that don't normally support it with compatibility flags and much more. It will also allow you to see all driver profiles that are available for your games and which settings they are set at.
1. Download and install the Nvidia driver profiling utility nHancer from http://nhancer.com.
2. Go to the nHancer Forum and check if somebody has posted a SLI profile for your game and/or enter something like [game name] nHancer SLI profile in your favorite web search engine.
3. If you find a profile, download it and double-click on it or open nHancer, click on Profile->Import and select the profile you have just downloaded.
4. Make sure to check override settings.
5. If you couldn't find a proper profile online, you will have to create one yourself.
2. Start nHancer.
3. Once it's done, enter the Application/game name in the dropdown box to see if there is a driver profile for it in existence.
4. If it is, proceed with step 10..
5. If it isn't, click on the Create a new profile Button.
6. Enter the name of the game/application for the profile.
8. Next to the Executables field, click on Add an executable to the profile(...).
9. Browse the folder you have installed your game in and select the game's .exe file.
10. Click on the profile for your game.
11. On the right hand side, click on the SLI Mode tab (if it's a DirectX9 game) or SLI DX10 tab (if it's a DirectX10 game).
12. Tick the checkbox marked SLI Mode (or SLI DirectX10 Mode for a DirectX10 game).
13. Experiment with the various options in the dropdown menu and the checkboxes in the Compatibility flags tab. It's a trial and error at this point, start the game and see how your settings affect it. It's generally wise to check which game engine a game uses and
14. I won't go into more detail about creating and tweaking profiles via nHancer here. If you have any questions or need further advice or assistance, I suggest to visit nHancer.com, sign up to the nHancer Forum and ask for help there.
I hope this guide will help the SLI users out there to enable SLI on their system and their favorite game(s).