My list:
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*crickets in the background*
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🤣
OK, I think there is only one: AMD Duron 1400 "Applrebred" that I bought either in late 2003 or early 2004... or thereabouts.
Before that, my parents had a Pentium II 400 MHz -based PC that we got around late 1999-ish (or early 2000?) I don't know if that PC was assembled with all new parts or from used/off-lease parts. I'd like to think it was all new parts, since I remember them mentioning that it was quite pricey at the time (despite a PII being rather slow / "outdated" in late '99 / early 2000 already.) It was the family PC until about late 2003-ish (or thereabouts, again 🤣), when I demanded we get a newer/better PC (i.e. the Duron Applrebred mentioned above.) Might sound like little me teenager was spoiled back then, but I can't say I was wrong to what I did. By late 2003, that PII with its 64 MB of RAM and Win98 was quite slow to do things online, and this is when schools were starting to push / experiment with online homeworks and whatnot. I also wasn't computer-savvy back then, so I didn't know if there was a better way to utilize that PII PC to do what was needed for school. So something better really was needed. Then the AMD Duron "build" came along. I put build in quotation marks, because I only got a CPU+motherboard+RAM+video card. Everything else was re-used from the PII PC. It was a bit of a horror build with extremely budget parts and many compromises, but it was my pride at the time. Ran Half-Life 2 at... embarrassingly low resolution and FPS 😁 . But I completed the game with it (and many others) without a hitch. So it was well worth it.
I also got the above AMD Duron PC messed up quite early in its life, mostly due to being a computer n00b and not knowing what do to online. Basically, I ran IE6 on XP (pre-SP / SP0) with no protection other than an old version of Norton AV, which caught absolutely nothing when the system was jumping full of viruses later on. It probably didn't help that in the same year I jumped onto the P2P scene like all the rest of my friends at the time (and probably their mothers too 🤣). Yeah, early 2000's 🙄 Piracy DID pay off off, though... I mean, ARRRR. 😁 - That is, it made me learn how to rid my OS of viruses and malware after getting infected with nearly every known trojan, virus, browser hijacker, spyware, and whatnot known to man. So in essence, I became "computer-savvy" through messing up my own system and then learning how to deal with it.
Of course, before I got to that level, my parents decided to "abandon" the above system (which was meant to be the family PC)... and I can't blame them for it (getting "weird" popups offering certain male enhancement products / pills, among other "services" was more than annoying 🤣 ). So they got a new system for themselves: a Dell Dimension 3000 with a pretty-new-at-the-time 2.8 GHz Pentium 4 Prescott. So that's new CPU #3 to enter the household (actually, #4 - there was a P4 laptop that my sister got for university the prior year.) After many years of service (up until 2015, IIRC), I finally upgraded them from that Dimension 3000 to a Pentium DC E2160... but that was a used CPU, and all of my PCs by then were the same.
So to recap, I think that makes the count to either 2 or 3 new CPUs, depending how one's counting:
1) Pentium II 400 MHz in late '99 or early 2000 (though not 100% sure if it was new)
2) AMD Duron Applebred 1400 in late 2003 or early 2004 (first and only new CPU I ever had)
3) Pentium 4 Northwood 2.8 GHz (sister's laptop in late 2004 or early 2005, IIRC)
4) Pentium 4 Prescott 2.8 GHz (non-HT / 533 MHz bus) in Dell Dimension 3000, serving from 2006 to approximately 2014/2015 as family room PC / parents's PC.
And that's really all.
After my AMD Duron PC became unstable (from bad caps in the PSU) in around 2007, I sort of left it aside and started using the parents's Dimension 3000 (this time I didn't mess it up, though 🤣 ... and if anything, actually took rather good care of it). The same year, I also started my collection of trashed / unwanted / broken PC from the neighborhood (most of them were just left on the side of the road by the trash or next to a dumpster. And with that, I have not gotten a new CPU or whole computer since. Just about everything I got was used.
As for prior to the Pentium II PC we got in '99... I don't really know or remember much details. I know we had a PC back at home as far back as '94/'95/'96, but I think it was through my mum's job (sort of as a "take-home" PC to work while employed.) There were several, actually. First one was your typical beige tower from the mid-90's with a Turbo button... so perhaps a 386 or 486-DX-something? Definitely not newer though. Came with a B&W (non-color) CRT, so who knows, though. A year or two later, it was a laptop... again, either a 486-DX-something or early Pentium and Windows 95. Then there was a short-lived (sort-of) Pentium 133 or 166 MHz PC from around '97 or '98 covering the gap until the PII PC in '99. I don't know if that was new or not... but if it was, then I suppose that would be #5 (or rather, #1) in my list of entries above. I was too little to know back then, though. So I'll leave the above list as-is for now. I also don't plan on buying any new CPU in the near future, so unlikely that my list will change anytime soon.