FYI. ACPI = Advanced Configuration and Power Interface.
It's the standard method for the OS/drivers to control system state including power (and by extension fan control). (And most implementations are extremely buggy).
http://en.wikipedia.org/wiki/Advanced_Configuration_and_Power_Interface
PS. There are a number of BIOS updates, with some mention of EPU (The Asus power unit), rebooting in some circumstances, and Q_Fan failure...
http://support.asus.com/Download.aspx?SLanguage=en&m=P5Q SE/R&p=1&os=25
Thanks for the ACPI definition, and for the ASUS link to the downloads page which I've seen before. I see a few BIOS updates that fixed problems that may be similar to mine, although not exact. Since I haven't had a freeze in 68 hours, I'm thinking that a BIOS update will not be necessary if I keep the function
disabled. This is why I asked you this
"So in your opinion, if anything on my MB that is involved with the fan speed control function is failing, then will disabling the function in BIOS Setup stabilize the MB, i.e. stop the freezes? I find it encouraging that a freeze hasn't occurred for 65 hours since the last one, or 60 hours after I disabled the function....."What do you think? Is the function really necessary in the first place? I've been checking the CPU core temp with Real Temp often, and with the function disabled I'm getting a 40 degree C reading for each core. I was getting the same reading with the function enabled with both Silent and Turbo fan rpm settings.
As a result of this thread, I remember the advice an ASUS tech. support rep. gave me on the phone as he walked me through the entire BIOS Setup settings step by step many years ago. I called about the looping boot process that never ended at the desktop, following my use of one of their CPU and case fan control programs. The advice from the company was
disable the function altogether. I don't remember if I questioned the advice, but maybe they were getting similar calls from customers who used their utility and had the same problem.
I have this gut feeling that my freezes have ended for good, so a "necessary" BIOS update will not be interrupted. But do I really need an update at all, since my only problem along has been the freezes? Any BIOS update is a risk, even in the best of times in the life of a pc.