I have to wonder at their claim that it works well with standard OEM gear. Even most cheap consumer shit monitors the speed of at least the CPU fan and tends to freak out if a fan that is supposed to be there is either absent or performing substantially below expected speed
Enter the BIOS (hit DEL during Power On Self Test), go into the Power or PC Health (depending on what BIOS you have). Alter the value of CPU FAN to "Not Monitored" or "Ignored". Hit F10 (or whatever yor key is) to save settings and reboot.
SpeedFan (etc) will still give you a speed readout if a fan is connected, but your BIOS won't complain if one isn't.
This procedure should be similar for UEFI based systems.