For an "exclusive" card pulled from an old enterprise desktop (e.g., HP or Dell branded Broadcom card), you may need to flash a "retail" firmware to remove whitelist restrictions.
[Brand Name] 802.11n Wireless PCI Express Card LAN Adapter – Exclusive High-Gain Edition 80211n wireless pci express card lan adapter exclusive
Speed fades. Reliability echoes.
However, here is what "exclusive" might refer to in this context, along with the best actual 802.11n PCIe adapters you can still find. For an "exclusive" card pulled from an old