Was here since...
I think an early Athlon Thunderbird.
Used to buy TONS of stuff from the MM, literally 100's most months. Was up as far as a Barton XP2200+ (1.83ghz) at 3.5ghz in a chieftec dragon case I'd shoehorned a vapochill PE cooler into (sat in the top where the second PSU space was, exhausted out of the top 3 5.25" drive slots. I thought it was epic at the time, possibly was for it's day).
Do wish I'd kept hold of the vapochill and got to know/understand it better for use in subsequent setups
I've kept hold of a well tuned 2600k for a good few years. Likely a Ryzen 1700 or lower end threadripper sometime later this year