OP tell us what you did and be honest. This does not happen by itself.

For the unfamiliar: Performance maximizer is Intel’s auto OC solution which works by dual booting from windows into small controlled boot environment. You have to install it and agree multiple times. Last time I’ve seen it was in 9900k era which makes sense with ‘this CPU is not supported’ message.

Now, if this was always happening just format the drive (or even better return it, it was used).

If you had everything working at first and then one bright idea too many you need to fix your EFI partition. Fastest is by booting off Windows install medium and going trough boot recovery or if that fails trough regular windows install. Your data will be fine, programs may require to be installed again.