“SpeedFan driver not installed” isn't an error. It's a eulogy for local control, spoken in a dialog box last seen in Windows XP.
Before you close this article, run through this final verification checklist to ensure the driver is actually installed. speedfan driver not installed
To understand the fix, you must understand the problem. SpeedFan was designed for Windows XP, Vista, and 7. It relies on a low-level kernel driver (usually WinRing0.sys or a similar direct I/O driver) to communicate directly with your motherboard's Super I/O chip. “SpeedFan driver not installed” isn't an error