PCIe Expansion
As stated on the previous page, the SFF OptiPlex had the capacity to add an additional NIC to the motherboard. I purchased an Intel I350-T4 NIC, which is a quad port gigabit NIC. I purchased the card for around $40.00 off of Ebay, but it had a full server height bracket. Adapter brackets are available via Amazon for $7.00. Below you'll find the NIC after I attached the half-height bracket.
Intel I350-T4 Network Interface Card
** There are many people selling fake versions of this card. Check out this link below to learn how to tell the difference between an OEM NIC and a fake!