May be a matter of preference, but in effect it is a myth, good example is that almost NO AMD mobos that run CPUs even support PCI-E 3, and new GPUs from both AMD and Intel are PCI-E 3. While PCI-E 3 cards are backward compatible to the PCI-E 2 slots AMD mobos utilize, and have enough open bandwidth to run (not to mention they have more PCI-E lanes), the AMD cards will run slightly better on the Intel platform. This is similar to other myths like GB GPUs run better on GB mobos (or Asus or MSI or others), or AMD DRAM runs better on AMD mobos (AMD DRAM is nothing more than rebranded Patriot and VisionTec sticks)