For RAM, CPU, Motherboard, and Hard Disk Tests:

MemTest86; https://www.memtest86.com/ Used for RAM health testing. An 8GB RAM test takes approximately 1 hour, and a 64GB RAM test takes approximately 6 hours. The free version is sufficient; for more detailed tests, the pro version costs $58 annually.

For Hard Disk Tests: CrystalDiskInfo (shows disk health and lifespan as a percentage) and CrystalDiskMark (tests read/write speed). You can also use HD Tune Pro to write data to the disk and check for errors. https://crystalmark.info/en/software/crystaldiskinfo/

For Processor (CPU) Pure Power and Stability Tests: Cinebench (measures processor performance by pushing it to its limits https://cinebench.net/) or Prime95 (finds hardware errors by pushing the processor to its limits https://prime95.net/).

For Graphics Card (GPU) Testing: FurMark https://geeks3d.com/furmark/ or 3DMark (checks for freezing or image distortion by pushing the graphics card to its maximum temperature https://www.3dmark.com/).

OCCT (The Most Effective PSU Test Tool https://www.ocbase.com/): For General System Stability: You can use OCCT software, which puts the entire system under load simultaneously while Windows is running. This software can test the processor, graphics card, and power supply (PSU).