SMBus: Is 100 kHz clock a risky frequency?
If I read the Wikipedia page about SMBus I read that:


  SMBus is derived from I²C


and


  SMBus clock is defined from 10–100 kHz while I²C can be 0–100 kHz, 0–400 kHz, 0–1 MHz and 0–3.4 MHz, depending on the mode. 


So it is simply a matter of definition that the SMBus clock should be 10 to 100 kHz.

It does not mean that a 1 Hz SMBus would not work. If you made your SMBus circuit such that it would work at 1 Hz, then it would. But then it does not meet the official SMBus specification so it would not be correct to call it an SMBus. But like I²C, it can work.