From which CPU family? The 440LX has a 66Mhz FSB interface. It'll take a PII up to 333Mhz, as that's the fastest PII which was made for a 66Mhz FSB. The fastest Slot 1 Celeron was 400Mhz w/ a 66Mhz ...
Precision Boost Overdrive (PBO) is a safe and easy way to increase CPU performance on AMD Ryzen chips. Enabling PBO provides a modest performance boost with potential gains varying based on CPU model.
Hmm, I think Sisoft Sandra usually helps. When it detects your motherboard, theres something called "Maxclockspeed xxxx" which *I think* tells you what the maximum CPU your motherboard can handle is.