I'm researching dual QSFP 40GBit network cards for a work project and have a few questions regarding PCIe 3.0's theoretical max bandwidth.
I'm currently looking at a dual QSFP PCIe 3.0 x8 card on CDW (Mellanox MCX314A-BCBT), but I don't think PCIe x8 would provide enough bandwidth for both 40Gbit links at 100% utilization.
Wikipedia states that PCIe 3.0 has a theoretical max bandwidth of 985MB/s per lane. Thus, by my calculations, PCIe 3.0 x8 would yield a max bandwidth of 7880MB/s. If this is true, the card would saturate the PCIe connection if both links are at 100% utilization.
Here are my specific questions:
What is the max bandwidth that a dual QSFP 40Gbit network card can output?
What is the max bandwidth that a PCIe 8x can handle before saturation?
Is there an easy way to calculate this?