I'm planning to install both a GTX 1080 Ti and a GTX 1080 in the same motherboard. The top PCIe slot has better bandwidth than the lower slot, so should I place the 1080 Ti in the top slot and the 1080 in the bottom slot, or reverse them? One concern is that some 1080 Ti models are exactly two slots thick while others are wider than two slots, which could prevent a second card from fitting when the Ti is installed at the top. I'd also appreciate clarification on whether using these two different GPUs together provides any meaningful gaming or upscaling benefit.
3 Answers
The cooler design matters just as much as the slot order. A card advertised as two slots wide may still have a backplate or fans that extend slightly beyond that space, while larger models can occupy three slots. Check the exact dimensions of both cards and the spacing between the motherboard’s PCIe slots before buying or installing them.
If both cards physically fit, put the GTX 1080 Ti in the motherboard’s fastest, upper PCIe slot and the GTX 1080 in the lower one. The Ti is the faster card, so it benefits more from the extra bandwidth. However, if the Ti’s cooler is thicker than two slots, it may block the lower slot, forcing you to install the 1080 Ti below and the 1080 above.
Two different GPUs generally won’t combine their performance through traditional SLI, and simply installing both won’t improve normal gaming performance. Some software can use a second GPU for specialized tasks such as frame generation or upscaling, but the gains may be small and compatibility varies. If you haven’t bought the cards yet, one newer, more powerful GPU is usually the better choice.
Also check the motherboard manual before deciding. The lower physical slot may run at fewer PCIe lanes, and installing a card there can sometimes affect other slots or storage connections.