I am sure you are having the same issue of mine with this LFKN server series.
IT is really weird that Intel did not provide a strait forward answer for this issue which it is standing on most of the server/workstation series.
Actually I have downloaded and tested firmware version S2600IP_W2600CR_EFI_BIOS02030003_ME020107328_BMC0120r5446_FRUSDR0112 which should solve this fan noise and speed but it did not solve this fan noise issue.
I hope Intel would read this post again and lead us to the proper solution.
Note that the website of Intel is now better but some information of technical support and download links are hidden somewhere if compared by the old website links.
Thanks for answering back if possible.