Cisco Networking – Line Protocol on Interface GigabitEthernet1/0/1 Changed State to Down

˙sɯǝlqoɹd ʎuɐ pɐɥ ɹǝʌǝu ǝʌ,I puɐ uʍop ǝpısdn pǝʇunoɯ ǝɹɐ sǝɥɔʇıʍs ʞɹoʍʇǝu ʎɯ ɟo ll∀

(Seriously: you should have no problem mounting a switch upside-down - just make sure you don't create any ventilation issues)

While banks of ports often share an ASIC, each has to have its own separate PHY. If the PHY has been damaged it could very have a problem while its neighbors don't.

That said, output drops are an odd symptom for a physical problem - not impossible, but not typical. Notwithstanding half duplex links, output drops usually have more to do with buffer exhaustion than physical problems.

You may get more information by setting up a packet capture on the other side of the wire. A bad PHY would be expected to manifest with some number of physical layer errors (bad CRC, runt/giant, etc) on one or both sides of the link.

All in all it sounds like you've eliminated enough that it may be past the point of diminishing returns. I'd recommend an RMA if you have a contract.