As most of us building our home labs are considering doing so on the cheap, it may be tempting for you to purchase a PCI NIC as a 2nd NIC for your host. Although this is cheaper (however not significantly) than a PCIe NIC, you may want to think about what you are doing.
PCI bus speed runs at 33Mhz x 4 bytes (32 bits) = 133MB/s. Gigabit Ethernet runs (maxing out) at roughly 100MB/s. So yeah, this could work. However, understand that the Bus speed is shared and that the likelihood that you will attain this speed in your lab diminishes as you may add more devices that share the bus.
PCIe is different and depends on the version of PCIe. the Capacity per lane (each direction) is the following:
- v1.x 250 MB/s
- v2.x 500 MB/s
- v3.0 985 MB/s
- v4.0 1969 MB/s
As you can see, PCIe is the way to go if you are adding in multiple NICs or devices onto your motherboard. Definitely look for a PCIe NIC that handles WOL if you plan on using WPM to cut power costs at home with hosts you are not utilizing.
I have picked up 4 TP-Link TG-3468 Gigabit PCIe NIC’s recently and have them running out of the box on my lab (ESXi 5.0.0) http://goo.gl/trU56
The best part is these NICs are only $12.60 which is only a few dollars more than your cheap PCI NICs.
Give them a shot!