How are PCIe 2.0/3.0 forwards and backwards compatible?

This doesn't make much sense to me, aren't different PCIe slots different sizes? I have an Asus P9X79 LE Motherboard (picture of board linked) and am trying to decide where to put the wireless card. The 'teeth' on the wireless card clearly fit what I think is the PCIe 2.0 slots (what's labeled on the board as PCIEX1_1, and the identical looking slot below it), but research has people talking about how PCIe slots are forwards and backwards compatible. Could I put such a small PCIe device in a 3.0 slot, leaving a huge chunk of the right side unfilled and it would work? This doesn't seem right. Do PCIe slots also come in different sizes, and my board simply has the x16 ones as all PCIe 3.0, and those two smaller ones as I think PCIe 2.0 and I think x4 length?
2 answers Last reply Best Answer
More about pcie forwards backwards compatible
  1. Best answer
    the two blue and one white are video slots. pci modes for video slots can be pci 2.0 or 3.0 speeds. depending on the mb chipset and the cpu that plugged in. the video ports can run from 16x mode down to 4x mode.
    the small slot is pci-express slot it can run at 1x mode or 4x mode.
    the last slot by itself is a pci slot.
  2. Thanks
Ask a new question

Read More

Asus Wireless Compatibility Motherboards Systems