I've been thinking about participating in #oldcomputerchallenge and even restored my first PC. But then I had a thought, a strange one.
The thing is, my main desktop which I use for all my work basically IS an old computer (for a modern audience). It has a motherboard from 2011, my CPU is from 2012 (DDR3, yep) and the newest thing I have in my case is an SSD. All PCI-E ports including PCI-E 1.0 are already fried, so I can't even install a GPU. Integrated video core from Intel works just fine.
That's a strange story. In some way it defies the purpose and at the same time reasserts it: you CAN use an old computer for all your work. Sometimes you might even not notice that.
There is no challenge.