Prime95 still has it's purpose, but be careful with it as with all stress testing. I guess you won't really know how stable a machine unless you stress it for many hours under different conditions. I usually make sure I'm rock solid by stress testing for MANY hours or a few days at a time when I can monitor the machine.
Many years and counting and I've never had a crash @ 4.6Ghz or 4.8Ghz + 1600Mhz RAM or 2000\2100Mhz ECC Server RAM. I Since this machine is so old now I run it at 3.8Ghz most of the time and can still get great FPS @ 4K with 2019 games WHILE recording. Can't wait for RDR2 to release on PC.