SLI / NVLINK Spacing Recommendations

Graphics cards need airflow and space to breathe to maintain decent temperatures. In SLI / NVLINK setups, the top card will always run hotter then the lower card. Why? Airflow. The lower card can draw in cool air while the top card draws in the cool air and exhaust air from the bottom card (does not apply if using a Blower cooled graphics card). Also, if the spacing in between the cards are restricted, the situation will only worsen for the top card.

Below are simple recommendations to ensure longevity and better overall performance when running an SLI / NVLINK configuration using open air designed graphics cards.

Simply, allow at least a 1 PCIe slot of gap/separation between the two cards (from the front of the cooler of the top card and the back of the backside/backplate of the bottom card).

If you're using a 2-slot open air cooled graphics card, use a 3-slot or 4-slot SLI/NVLINK bridge.

If you're using a 2.5/3-slot open air cooled graphics card, use a 4-slot SLI/NVLINK bridge. While a 3-slot bridge can work, the airflow will be too restricted and the top card will suffocate and is simply not recommended.

Refer to this landing page for visuals - https://www.zotac.com/page/zotac-gaming-geforce-rtx-nvlink-bridge

Also, while this doesn't apply widely, it is still good to mention and good to practice.

The bottom card can also suffer due to space limitations. We've seen builds where the bottom graphics cards are millimeters length away from the power supply at the bottom of the computer. This isn't good either as mentioned above, it will draw in cool air and exhaust air from the power supply in addition to being in a position to suffocate due to the more limited spacing and lack of airflow. There isn't much that can be done in this situation other than using a larger chassis.

If you're building your system and plan to SLI / NVLINK two cards, plan ahead of time else performance can take a hit and the longevity of the graphics card will shorten too.