I have the Crosshair VIII Formula with a 5950X, G.Skill 3600 CL16 RAM and I'm on 3501.
I have progressed from a 3950X to the 5950X and several of the initial 5-series BIOS seemed to have issues.
After a few tweaks I'm running an all-core OC at 4.5GHz and DOCP running the RAM at full speed.
I run many video encodes for which the all-core OC works much better than the PBO options.
I recently upgraded GPU to a Gigabyte 3080TI Gaming OC and it has worked flawlessly. I get great Cinebench and 3D-Mark scores and more importantly, it runs stably with Handbrake H265 4K encodes which take several hours - sometimes at 90%+ CPU utilization. Temps average 70C at the highest.
As it is, nothing is broken - it's doing everything I want/need it to do. Unless/until there's a specific reason to upgrade, I'll stick with 3501.