Yep, my Support case just came back with that Bug. I'll try applying that to the machines where I have already disabled ACP, then re-enable ACP to see if it keeps the IO down.
Remove checksum firmware files from "/mroot/etc/acpp_fw". Specifically removing
following files will avoid this issue:
* ACP-IOM3.xxxx.AFW.FVF
* ACP-IOM6.xxxx.AFW.FVF
where; "xxxx" is the firmware file version.