See screenshot. I'm pretty sure that the numberin is different argus vs HWMonitor here. Looks like:
CPU in HWM -> Fan 1 in Argus
SYS1 -> Fan 3
SYS3 -> Fan 5
SYS6 -> Fan 8
Does that seem right? Why is the numbering different? I think the HWM numbering follows how the headers are identified...