Oldest in permanent use was probably 5 years with a Phenom II Xsomething with a GTX 280 during the time i barely had interest in new games, lasted me until 2014 when i bought a new PC finally.
threw that out a long time ago.
I still have my old 486 DX4 100 MHz (AMD version) with a ATI Mach 64 GPU (4MB), 16 MB of Ram and a 130 MB HDD and a 1 GB HDD. It was upgraded from a 386, same case, same original HDD, it still contains a lot of my old save games, early attempts at programming in Qbasic (text adventures, simple graphics, nothing fancy) and all that. Of course i rarely used it over the last few...decades, but it still works, even the PSU is the same old one.
If the Ram and GPU Crisis continues, i guess my current PC will have to last for a decade, thankfully i did buy 64 gigs of ram and a 20 gig GPU, so it will work for a while

(Of course looking back, the numbers are insane. in 1996 i thought the 1 gig HDD would last forever. In 2000 i thought the 20 gig maxtor in our Pentium 3 is overkill, when i had my first 1 TB Drive i thought "where does it stop?" and now i have 8 Terrabytes of NVME and go "I need more!" * same with ram, same with everything)