PCIE Lanes

How does the available PCIE Lanes in my processor affect my ability to SLI or Crossfire?

Steve Smith talks about PCIE lanes, and why knowing what you need may prevent issues with bandwidth on your new mainboard.

Episode #5-16 released on January 9, 2015

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This is a newer issue related to PCIE Graphics cards, and it is directly related to two different specifications related to both Nvidia's SLI Standards, and ATI's Crossfire Standards.

There is one thing many consumers do not know about processors and motherboards, a lot that could fill an entire inbox of questions, if you only knew.

For one, very few people know that all processors have a maximum number of available PCIE lanes. Secondly, the number of cards based on the GPU architecture, is largely dependent on the number of available of PCIE lanes, the standard itself, and how many other features your current motherboard may have.

Take the time to read your motherboard's manual, and you may have many warnings related to SLI and Crossfire indicating how under various circumstances, entire feature sets may be turned off just to get your system to work properly with all of your components inside. Nothing is guaranteed to work just because you plug it in, and various add-on peripherals may not be allocated their necessary bandwidth to be able to be used by your system.

What does this mean for your average consumer?

I have seen it often, people buying the wrong boards and processors thinking it can upgraded down the line. Buying parts suited to your situation now, and in the future is the best way to avoid issues and bottlenecks related to possible future upgrades. This does mean that you have some research to do before buying any specific pieces, and do not necessarily settle on the cheaper outdated gear from large chain stores, as the performance of those devices will greatly vary, and more than likely be far less capable than you initially wanted.

Are there any suggestions?

For most gamers, consider buy a single better graphics card than many cheaper cards to put into your system. You will reduce the requirements for your power supply, have less heat in your computer chassis, benefit from better features and smoother images, and be able to run all games from the get go without the need of special SLI and Crossfire drivers. Buying many smaller cards can look to be less expensive, but it does come with the possibility of costing more in the long run, and not necessarily giving you the experience you expected.

Wait, what about PCIE Lanes, how many does my processor have?

This depends on your processor. If we take the i7-4790K, a processor I have, it only contains 16 PCIE express lanes. Which means that I can use up to 16 PCIE lanes, this does mean that while I can SLI, I end up cutting the bandwidth in half per card. A single graphics card could get 16x, while two would benefit from 8x each. Currently, running to modern 900 series Nvidia Graphics cards will not bottleneck, even at 8x, so SLI without loss of performance is possible, but if I connect other add on card the performance of the graphics cards may be lowered, and some features of the mainboard may be deactivated.

Which brings us to the last point. The features of your mainboard may be just as important, in some cases, as the possibility of upgrading. If you can refrain from adding an extra PCIE addon card, you may be able on some boards to use SLI or Crossfire for fear of features being turned off, but please, read the manuals of any mainboards you are interested in purchasing, they are available in the downloads section of any manufacture's web-site.

Host : Steve Smith | Music : Jonny Lee Hart | Editor : Steve Smith | Producer : Zed Axis Productions

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