Nvidia SLI And AMD CrossfireX Setup Guide

Selecting the Correct PCIe Slots

Each motherboard will have its own unique PCIe lane configuration. The total number of lanes available is dependent on the CPU/chipset of the motherboard. If possible it is best to place each graphic card in a PCIe 16x slot, but not all motherboards will have that facility. Those motherboards that do support 2 or more PCIe 16x will often place the two 16x where it best suits a mutli-GPU layout. It therefore does not always follow that the first two slots will be both 16x; more often the first and third slot will be 16x. The PCIe configuration of your particular motherboard will be laid out in the motherboard manual or you can physically check the markings on the motherboard itself if you like.

It is worth noting that some of the modern super graphic cards, such as the MATRIX and DirectCU II ranges are triple slot graphic cards. What that means is the graphic card will take up three slots in the case, rather than two. So if you are pairing two of these high-powered behemoths, please ensure your motherboard has a suitable gap between PCIe lanes to accommodate them.

1st slot = DP, DVI, HDMI; 2nd slot = DVI, Safe Mode, heat exhaust; 3rd slot = heat exhaust

Power Requirements

A graphic card is a major user of power. It is for that reason that PSU manufactures rate their products as SLI and/or CrossFire certified. It is in your best interests before embarking on the dual graphics card journey to ensure your PSU will be up to the task, otherwise it will not have the necessary power connectors, or worse yet, your system will crash. Most PSU manufactures will clearly show if the PSU is SLI, CrossFire or multiple graphics card ready.

The total number of connectors needed to power the two cards needs to be factored into your configuration.  There are adaptors available if your PSU does not have sufficient connectors, but it’s not recommended to use this method.

*Warning – only connect PCIe 6/8-pin connectors to your graphic card. Make sure you are not trying to connect a 12v motherboard 8 pin connector to your graphic card. Most PSU vendors clearly mark their cables and connectors: 8-pin motherboard connector is labelled ‘EPS’ or ‘ATX12V’, whereas 8-pin graphics connectors are usually labelled ‘PCI-E’.