FAQ

What is NVIDIA SLI? How does it work?
NVIDIA® SLI™ is a high-performance technology that intelligently combines and scales graphics performance and visual quality by having multiple NVIDIA GPUs in a single system. SLI Technology can scale both geometry and fill rate performance for two GPUs.

How is SLI different from competitive product offerings?
SLI technology is the only multi-GPU solution that was built from the ground up with dedicated scalability logic in each GPU. This logic enables the most efficient communication between GPUs providing the best scalability performance. SLI technology also has the most comprehensive list of supported games.

Do you have dedicated hardware for NVIDIA SLI or is it just software?
Yes. NVIDIA GPUs combined with an NVIDIA nForce® SLI motherboard (which ships with the proprietary NVIDIA SLI connector) are the necessary building blocks for the SLI platform. Dedicated scalability logic in each GPU and a digital interface between GPUs (the SLI connector) enable this logic. In addition, a full software suite of advanced rendering algorithms provide the best image quality.

How much of a performance increase will I see with SLI technology?
The amount of performance improvement will depend on the application and its ability to scale. Several of today's hottest games see a full 2x increase in performance when using SLI technology with two graphics cards. 3-way NVIDIA SLI technology enables up to 2.8x performance increase over a single GPU. In general, applications running at higher resolutions with higher image quality settings will benefit most.

How does this technology differ from 3dfx's SLI?
NVIDIA SLI differs in many ways. First, 3dfx SLI was implemented on a shared bus using PCI. The PCI bus delivered ~100MB/sec. of bus throughput, while PCI Express is a point-to-point interface that can deliver ~60x the total bandwidth of PCI. Second, 3dfx SLI performed interleaving of scan lines, and combined in the analog domain, which could result in image quality issues due to DAC differences and other factors. 3dfx Voodoo technology also only performed triangle setup, leaving the geometry workload for the CPU, hence 3dfx SLI only scaled simple texture fill rate, and then used inter-frame scalability. NVIDIA SLI technology is PCI Express based, uses a completely digital frame combining method that has no impact on image quality, can scale geometry performance, and supports a variety of scalability algorithms to best match the scalability method with application demands.

Does SLI work on AGP?
No. SLI is designed for PCI Express.

How does SLI work on PCI Express?
SLI is designed for PCI Express. This new bus has superior bandwidth (two to four times AGP 8X), support for isochronous data transport, and the capability to drive multiple high-speed graphics devices. AGP 8X was limited to one high-speed graphics device and was not a good candidate for SLI.

What graphics cards support SLI technology?
The list of SLI-Ready GPUs can be found here. A complete list of certified SLI-Ready graphics can be found here.

For information about SLI technology for NVIDIA Quadro graphics solutions, click here.

What is the function of the SLI connector?
The SLI connector is a proprietary link between GPUs that transmits synchronization, display, and pixel data. The SLI connector enables inter-GPU communication of up to 1GB/s, consuming no bandwidth over the PCI Express bus. The SLI connector is used with GeForce 6600 GT products and above. For all other SLI-Ready graphics cards, inter-GPU communication is passed through the PCI-Express Bus, instead of through the SLI Connector. For these mainstream GPUs, there is typically enough excess bandwidth across the PCI-Express bus to effectively manage this additional communication. More powerful GPUs require the SLI connector to achieve optimal scaling results.

SLI FEATURE SUPPORT

What operating systems are supported with SLI Technology?
SLI technology supports the following operating systems:
  - Windows XP 32-bit
  - Windows XP 64-bit
  - Windows Vista 32-bit
  - Windows Vista 64-bit
  - Linux 32-bit
  - Linux 64-bit (AMD-64/EM64T)

What applications are supported with SLI Technology?
SLI can be enabled for every gaming application, providing either performance scaling results through AFR or SFR rendering modes or increased visual quality through the SLI Antialiasing mode. In order to provide the optimal 'out-of-box' experience for its customers, NVIDIA has created an extensive set of optimized game profiles which enable SLI automatically. The full list of these SLI-optimized games can be found here. For applications not found in this list, simply follow these quick instructions to set up a new game profile to enable SLI. Information about Workstation application support can be found here.

Which driver should I use?
NVIDIA® ForceWare® Unified Driver Architecture (UDA) supports SLI technology. Simply download the latest GeForce or Quadro graphics driver from www.nvidia.co.in.

NVIDIA continually adds new SLI applications profiles to upcoming drivers. For the most up-to-date SLI application support, always use the latest drivers.

Before installing new drivers, make sure you uninstall all NVIDIA display drivers from the Windows Control Panel. Browse to the Start Menu > Windows Control Panel > Add/Remove Programs, and search for "NVIDIA Drivers" or "NVIDIA Display Drivers," and select remove NVIDIA Display driver only. Reboot and install the new drivers.

Why don't all games see performance increases?
Applications which tax the GPU will see tremendous performance improvements of up to 2X with SLI technology. Most of today's hottest games and as well as next generation games fall into this category. However, some applications, typically older generation applications, are limited by factors other than the GPU's processing power.

The most common limitation is an application that is CPU bound. If an application becomes CPU bound, no additional graphics power can improve performance. This situation is most common at low screen resolutions like 1024x786 with no additional functionality turned on. Turning on Antialiasing and Anisotropic Filtering, or switching to higher resolutions, can often move the bottleneck back to the GPU.

For CPU bound applications, NVIDIA offers a new SLI rendering mode called SLI Antialiasing. This rendering mode allows customers to enable SLI8x or SLI16x antialiasing and enhance the visual quality of any gaming application.

What is SLI Antialiasing?
SLI Antialiasing is a new standalone rendering mode that offers up to double the antialiasing performance by splitting the antialiasing workload between the two graphics cards. When enabled, SLI Antialiasing offers 2 new antialiasing options: SLI8x and SLI16x. In the current driver, this rendering mode can be enabled by following these quick instructions. More information about SLI Antialiasing can be found here.

Is NVIDIA working with Developers on SLI application support?
Yes. NVIDIA is actively working with developers and educating them so that their titles can benefit from SLI as much as possible. By developing future titles on SLI technology, game developers are able to optimize their titles for SLI configurations. Additionally, the performance of SLI today gives developers a glimpse of how tomorrow's single GPU systems will perform. This allows them to tune for all elements of the system including CPU utilization.

How many monitors are supported when running in SLI mode?
When in multi-GPU mode, SLI currently supports one monitor. When in single-GPU mode, users have the ability to use all of the connectors on their GPUs to connect to monitors using NVIDIA® nView® multi-display technology and Windows built-in multiple display support.

How do I switch from using two or more monitors in 2D/single GPU mode to one monitor in SLI mode?
You can switch between these modes by enabling or disabling SLI technology in the 'NVIDIA Control Panel’ (right-click on your desktop to open). With Release 80 graphics drivers, this switch no longer requires a restart of your PC.

Can I output to my TV or HDTV in SLI mode?
Yes. GeForce 6, 7, and 8 series SLI configurations support HDTV modes. However, GeForce 6 and 7 GPUs are limited to only support HDTV progressive modes with SLI enalbed (480p, 720p, and 1080p). For more information on the limitation on GeForce 6 and 7 series, please read this NVIDIA Knowledge Base article.

What are the SLI Visual Indicators?
If you see horizontal or vertical green lines on your screen (shown here), it means that you have "Show SLI Visual Indicators" enabled in the NVIDIA Display control panel. When enabled, this option shows how your GPUs are sharing the graphics load and will overlay the name of SLI in your system: two GPU SLI will over “SLI”, 3-way NVIDIA SLI will overlay “SLI x3”, and Quad SLI will overlay “Quad SLI”. For games that are rendered using alternate frame rendering (AFR), a green vertical bar will grow up and down on your screen, depending on the amount of scaling. For games that are rendered using split-frame rendering (SFR) , a green horizontal line will move up and down on your screen, showing how the load is being balanced between each GPU. If the upper half and the lower half of the screen have a similar level of detail, the horizontal line will stay close to the middle. To enable or disable this feature, simply open the NVIDIA Control Panel and select 3D Settings. With the 3D Settings page open, click on the 3D Settings tab in the upper menu bar (shown here)

Can I use Coolbits for overclocking AND the expanded SLI functions?
With Release 90 or later ForceWare graphics drivers, Coolbits is no longer required for advanced SLI functionality. However, users can still use Coolbits to enable graphics cards with different memory sizes to work together in SLI mode. To enable this feature, along with overclocking functionality, set Coolbits to 1A.

What operating systems does 3-way NVIDIA SLI support?
3-way SLI will only be supported on the Windows Vista operating system. This includes 32-bit and 64-bit versions.

Note: The GeForce 6800 Ultra 512MB works in single card mode ONLY with a limited number of widescreen displays. This is due to an interaction between the GPU, the application, and the ability to scale to nonnative panel resolutions.

NVIDIA recommends using single card mode for the GeForce 6800 Ultra 512MB when combined with the Apple 30 inch Display or the HP L2035 Display.

CONFIGURATION SECTION

What motherboards will work with SLI Technology?
The full list of SLI-Ready motherboards can be found here. This list is updated frequently with new SLI-Ready partners.

What graphics cards support SLI technology?
SLI is designed for PCI Express and not AGP. This new bus has superior bandwidth (two to four times AGP 8X), support for isochronous data transport, and the capability to drive multiple high-speed graphics devices. The full list of SLI-Ready graphics cards can be found here. This list is updated frequently with new SLI-Ready partners.

Can I mix and match graphics cards?
In order to provide optimal symmetric scaling, SLI technology requires the NVIDIA GPUs to match. For example, a GeForce 7800 GTX must be paired with another GeForce 7800 GTX. Likewise, a GeForce 6600 GT must be paired with another GeForce 6600 GT. However, using the latest Release 80 or later graphics drivers, NVIDIA GPUs sold by different manufacturers can be used together in an SLI configuration. For example, a GeForce 7800 GT from vendor ABC can be matched with a GeForce 7800 GT from vendor XYZ.

Can I mix and match graphics cards is one of them is overclocked by the manufacturer?
Yes. A GeForce 7800 GTX that is overclocked (for example BFG GeForce 7800 GTX OC) can be mixed with a standard clocked GeForce 7800 GTX.

Can I mix and match graphics cards with different sizes of memory?
While it is not recommended, NVIDIA does offer this flexibility using Coolbits. When purchasing a second graphics card, you should try to match the memory size so that you are ensured full value and performance from your purchase. For example, if your first card is a GeForce 6600 GT with 128MB of memory, you should purchase a second GeForce 6600 GT with 128MB of memory. However, using Coolbits (value set to 18), you can force both of the cards to use the lower of the two memory sizes and operate together in SLI mode. When dissimilar memory sizes are enabled to work together using Coolbits, the effective memory size for each card becomes the smaller of the two memory sizes. Instructions to enable this feature can be found here.

Do other graphics card features such as VIVO need to match?
No, you only need to match the NVIDIA GPUs (for example GeForce 7800 GTX) for SLI technology to work. As mentioned above, NVIDIA also recommend that customers match the memory size to ensure that they get full performance and value out of their graphics card purchase.

Does SLI technology also work with four GPUs?
Yes. Quad SLI technology supports four GPUs in SLI mode. Learn more about Quad SLI technology here.

Does SLI technology also work with three GPUs?
Yes, this is called 3-way NVIDIA SLI technology and it supports three GPUs in SLI mode. Learn more about 3-way NVIDIA SLI technology here.

Where can I get a 3-way SLI connector?
For users that have an existing nForce 680i motherboard that need a 3-way SLI connector, there will be several partners offering the connectors for sale. Please check this website for more information http://www.slizone.com/object/slizone_3waysli.html

Do I need a new power supply if I am building a 3-way SLI PC?
3-way SLI requires a power supply that means the total power requirements and has six PCI-E 6-pin power connectors. Please visit the Certified SLI power supply section on SLIZone.com

Can SLI work with one PCI Express board and one AGP 8X board or with PCI Express and PCI?
No. SLI is designed solely for PCI Express.

Can I install just one SLI-Ready graphics card with an NVIDIA nForce4 SLI based motherboard?
Yes, NVIDIA nForce4 SLI based motherboards can support any single PCI-Express x16 based graphics card. Two graphics cards are not required but recommended. For the best experience and upgrade potential, make sure to use an SLI-Ready PCI-Express graphics card. Always look for the SLI-Ready logo.

Where can I purchase an SLI connector?
The SLI connector is included with all NVIDIA SLI-Ready motherboards and with all SLI-Ready PCs. If your motherboard supports SLI and did not come with this connector, please contact the manufacturer of your motherboard to obtain a replacement connector.

What power supply does NVIDIA recommend for an SLI system?
NVIDIA has extended its SLI-Ready certification program to include power supplies. The full list of SLI-Ready power supplies can be found here. In general, power supply recommendations vary widely depending upon the configuration and the desire for future upgradeability. More information about power supply selection can be found here.

Can you use more than two graphics cards with SLI?
NVIDIA currently supports only dual GPU scaling at this time.