In my experience, I have had NICs, HBAs, and many other cards go squirrely after 12-18 months of uptime, so when doing a scheduled maintenance or BIOS upgrade, I like completely removing power (as in unplugging it, waiting 60 seconds for the capacitors to drain, and replugging.) This has solved problems on almost every hardware architecture I've seen, be it IBM POWER, SPARC, PC, Macs, RAID arrays, NAS models, SAN models, SCADA systems... you name it.
It has become one of my troubleshooting procedures. NIC acting wonky? Power the machine off, remove power completely, wait a little bit, plug back in. Then it works.
Power cycles are not just for Windows.