Since 2008, I've been finding Riesel primes using my personal hardware. I added aliquot sequences to that in 2014. Off and on in that span, I've contributed to GIMPS, most recently doing ECM and PRP tests on small composite Mersenne numbers, along with trial factoring.
My earliest project was the Riesel Prime Search (RPS). I briefly worked on the k values 19 and 37. Most of my work has involved filling in gaps in the Riesel and Proth Prime Database, particularly for k values between 10,000 and 15,000 and the RPS 9th and 10th Drives.
Following from my interest in factorization, I started working with aliquot sequences in December 2014. I generally work with cofactors under 120 digits, given my hardware limitations. I have terminated 1 sequence, 2047472, on one happy October 2018 night.
The computer I used when I first started was a 2006 HP desktop. It had a 2.2 GHz AMD Athlon 64 X2 4200+ CPU (64 KB / 512 KB L1/L2 cache), 2 GB of RAM, a 250 GB HDD, and a 32-bit version of Windows XP. Unfortunately, just a year later, the PSU and mobo melted while I was taking an exam.
Most of my work has been done on a 2009 HP desktop. It has an Intel Core 2 Quad Q8300 CPU (no VT-x, unfortunately), 8 GB of DDR3 RAM, a 750 GB HDD, a 300 W PSU, and no useful GPU. It came with Windows 7, but it has run various versions of Kubuntu since I first got the computer. Right now, due to its old CPU, it primarily works on Riesel prime sieving, GIMPS, and aliquot sequences. It also serves as a PRPnet server for my home network.
Today, my other primary computer is a 2014 HP laptop. Its hardware sucks (the trackpad is awful, and the touchscreen is useless), but its Intel Core i3-4012Y CPU, despite have a much lower clock speed than my primary desktop, can process LLR much faster due to its AVX2/FMA3 support. It came with Windows 8.1, and I upgraded it to Windows 10 when that was released. (I hated Windows 8.) In September 2019, Windows was rendered unable to boot due to a HDD issue, so I wiped it and replaced it with the Kubuntu LTS release (18.04 at the time). It exclusively runs LLR tests on Riesel prime candidates (through PRPnet) when not in use.
I briefly also ran LLR on my brother's laptop (also made by HP), but it proved to be too unreliable and hard to access from my server. It has an Intel Core i5 of some sort, and it's actually faster at running LLR than my own laptop.