In case anyone from Italy stumbles upon some old oscilloscopes branded as TELAV1 (sometimes misread as TELAY due to the horrible graphic design of their logo):
They are all rebranded Hung Chang oscilloscopes, especially the “TELAV 09635” (a rebranded “Hung Chang OS-635”) and the “TELAY 09620” and “AWS MODEL 620C”2 (both rebrands of the “Hung Chang OS-620”).
It turns out that the PWM signal on PC fans doesn’t require much current. Max 5mA according to the Intel specifications.
The trick is to place a driver inside the fan capable of obtaining the necessary voltage/current.
This exonerates the MoBo engineers from accounting for high current requirements when designing the PWM controller and avoids wasting energy driving up and down a potentially high current through the connectors and cables.