I actually have quite a few old computers for different reasons.
1. A retro Win98/XP gaming computer with a PIII 1GHZ CPU, 1GB of RAM, and a 64MB Geforce 4 Card. -15-17 years old Gaming PC
2. A retro Windows 2000 workstation with a P4 3.4GHZ CPU, 2GB of RAM, Quadro 3000 256MB GPU, and 2x 15000RPM SAS Drives (36 & 72 GB). -13 years old for 3DS Max 5 and Maya 6.
3. Retro Windows XPx64 workstation with 2x Opteron 285 2.6GHZ Dual Cores, 6GB of ECC RAM, Quadro FX4600 768 MB, 2x WD Raptor 10000RPM 300GB SATA Drives. -12 Years Old for Lightwave 3D 8.5 and 9.3
4. Dell Precision t5400 Vista Ultimate workstation with 2x Xeon 5450 3.0GHZ, 16GB of ECC RAM, Quadro FX 5800 4GB, 2x 15000RPM SAS 300GB Drives. -10 Year old Workstation for 3DS Max 2009 Student and Blender 3D, and benchmarking GPUs.
5. I have not put it together yet but I have a Vista gaming build with a Core2 Quad Q9650 3GHZ, 8GB of RAM, 3x GTX 9800+. -10(ish) year old system to compare professional hardware to.
6. Windows 7 gaming build with i7 940, 12GB of RAM, variable GPUs. -8 year old gaming PC which is also used to benchmark DX11 GPUs.
I want to build myself a Dell Precision t7600 and load it with 2x Xeon 2690s, 32-64GB of ECC RAM, 2x Tesla 2075 and a Quadro k5000, with a couple of SSDs to simulate an early GPU rendering system. But I do not have the moola for that right now, what with other expenses I have to worry about right now. - 5 year old System for 3DS Max 2014 and Blender 3D.
For comparison: My actual workstation is an HP z620, 2x 2680v2, 64GB ECC RAM, 2x Asus 1070 Turbo (NO! This system does not support SLI with these cards, they are for rendering in Redshift), 4x 512GB SSD, Windows 7 Pro. I plan on adding a PCIe SSD for Rendering/Simulation Cache and either replacing the 2 Geforce cards (and putting them into my rendering NODE) with Quadro P/V 4000s or replacing only one of them with a Fire/Radeon Pro card since their drivers (which I need) mix well with Geforce cards while Quadro's cannot.
-1-4 years old with parts from many different years that I use for Maya 2016, Redshift, Blender 3D, Photoshop CS6, ZBrush 4r8, Painting 2016, and finally Substance Painter 2018. I will get 3D coat soon for its strong retopology tools.
Look at that wall'o'text, I made dis, yeeees.