What software to use for load testing?

Question

Windows Server

Windows Server 2016 Standard, which is mainly used on an average of 10-15 people applications: RDP, DBMS (microsoft, postgresql), 1s, office suite.
Performance counters. perfmon. configured and working. There are no server load counters, but in addition I want to use some load test to see how the server generally copes with test and stress loads. From what I want from software, this is complexity, that is, to load to the maximum and on average all components of the processor, RAM, disk, network, and, if possible, free software. From what I have tried so far, though a paid trial, "SiSoftware Sandra Lite Platinum.SP4". It produces completely abstract indicators that are not clear with what to compare. Only on the disk showed "live"