No, don't OC a server (even if you could). Servers are about stability. I see your SSDs are in RAID, I was just wondering if you were using any HDDs as well.
ECC RAM is inherently slower than non-ECC RAM, but you shouldn't worry about that. Servers are all about accuracy and stability. The ECC features help with the accuracy issues.
Are you using that rig as a server, or as a workstation? Also, what type of network connection is this system accessing the Internet with?
Last, are you using a custom app or a commercial app?