xeon workstation questions

I was thinking about dual cpu ES E5-2697 v4 or 2699 or 2696v3 on modded bios. Are there now modded bios so we could run v4 on all cores turbo like on v3?
I have around 2,5k EUR. Next option is better one cpu and in some time buying second one. Or it will be best to go for a threadripper setup?

Do you guys encounter this issue with 2 cpu pc used as a workstation, not a node? https://forum.corona-renderer.com/ Dual cpu speed problems #msg127014

Thanks