updating your BIOS should not disable your Ryzen 5 2600 CPU. However, it's always a good idea to double-check the compatibility of your specific CPU with the new BIOS version before updating. Check your motherboard manufacturer's website for information on which BIOS versions support your CPU.
Updating your BIOS may potentially improve performance, but it's not guaranteed to solve the issue. Other factors, such as driver settings, software conflicts, and hardware compatibility, can also impact performance. It's possible that your issue may be related to something other than your BIOS.
Here are some other things you can try to troubleshoot the issue:
Update your graphics card drivers: Make sure you have the latest drivers installed for your RX6800. You can download the latest drivers from AMD's website.
Check your graphics card settings: Make sure you have the correct settings configured for your RX6800 in the AMD Radeon Software. You can try adjusting settings such as anti-aliasing, tessellation, and texture filtering to see if it improves performance.
Monitor your system performance: Use a system monitoring tool to track your CPU and GPU usage, as well as your system temperature. This can help identify if your CPU or GPU is the bottleneck, or if there are other performance issues.
Reinstall Overwatch: It's possible that the game files may have become corrupted during the transition from your GTX 1080 to your RX6800. Try uninstalling and reinstalling the game to see if that helps.
If you've tried these steps and still experience poor performance, it may be worth waiting until you upgrade your CPU to see if that solves the issue.