When homebrewing a CPU, one has to deal with microcode. Microcode is the low-level nuts and bolts of how, precisely, a CPU executes instructions (like opcodes) and performs functions such as updating ...
Your system might have firmware updates that you never knew about.
Historically speaking, even when it wasn't the absolute fastest option, Intel has always been 'competitive' with longtime rival AMD in terms of CPU gaming performance. That is actually still the case ...