No, both controllers are fully supported in the 850. I would suggest updating the system firmware before the install though (BIOS and ESM first, then other system firmware).
Alright so I've been battling a 4/SC perc for a day or so to find that it is not compatible with 2008 r2. I need to upgrade it to 4e/DC I believe. Is their any hard ware conflicts I need to be aware of ? Is their a process to replacing a raid controller that I need to be aware of? Where is the best place to purchase a 4e/DC ? aswell I understand this system is old and replacing the system would be easier but I was handed the project of getting this upgraded and I do not like to disaapoint.  any information you think I'd useful would be appreciated.
Dell Poweredge 850