All core should be it's base clock of 3GHz. Even though it's a locked chip, you should be able to increase that either in the BIOS or by enabling the "high performance" power plan in Windows - I don't think you'll sustain 4.7GHz though.
As far as an "upgrade" goes, is RDR2 maxing out your 8500? If not, then it's not likely to make much of a difference.
I don't know because it's not out yet.