I have 3 disks in my PC : one 500 GB SSD for the system, and two 3 TB HDD for the data (mostly pictures RAW files). All are monitored by CrystalDiskInfo, which does not report any problem.
Again, Speccy returns normal operating temperatures: 40 ° C for the discs, 58°C for the graphic card, 25°C inside the PC box. Dust has been removed, all 3 fans checked (main fan, CPU fan, graphic processor fan).
I will open the PC again to add thermal paste on the CPU.
@G3PIY : Windows 10 was installed on the SSD after formating it. All other programs were installed after.