reply to daveinpoway
Re: Supermicro motherboard beeping For the new Heatsink/Fan you installed - have you confirmed the fan type is the correct one for your motherboard?
i.e. Tachometer based vs. PWM based fans
Assuming that you didn't change any of the case fans (and that they haven't failed), I'd be betting on the changes being the cause of any new issues.
Yes, the new heatsink fan is a 4-pin (PWM-controlled) type and the package indicates that it will work for a Socket 775 application. The heatsink is a massive thing with a 110 mm fan (intended for gaming PC's), so it should have no problems cooling my system. If I feel the heatsink fins, they aren't even warm.
One thing which doesn't make sense to me- the Supermicro rep indicated that the BIOS may not report the temperatures accurately. The question is: If the BIOS does not accurately know how hot the CPU is, how does it correctly know when it should activate an overheat alarm? I suspect some sort of BIOS bug(s), since the BIOS version I am using is very old. Updating to a later version doesn't work for me, since someone apparently rewrote the fan-speed code, causing the rear case fan to turn significantly faster in the later BIOS versions. The faster speed causes the noise level to be unacceptable for the location of the system.
I suppose that something could be wrong with the rear case fan tachometer circuit, but the BIOS shows a speed reading that makes sense, so everything seems to be fine. As I indicated earlier, I will try plugging the rear case fan into a different motherboard connector if the beeping returns. I don't presently have another 120mm 4-pin fan to try.
If I was really brave, I could take the later BIOS code and edit it to lower the rear case fan speed, but one mistake and the board will be ruined. I will leave BIOS editing to the experts (I have never done it before).
Just pulled up the manual for your motherboard - PWM fans should be fine.
If it is an overheating warning, there's also an overheating LED on the motherboard (LE2 beside the CPU) that should light when the warning sounds. The manual only mentions beep codes for video, memory or overheating - other error codes would attempted to be displayed at the top left corner of the display.
There should be a BIOS setting for 'CPU Overheat LED and Control' where you should be able to set the CPU temperature threshold.
You could try setting the temperature threshold lower in order to intentionally generate the overheat warning tone at a lower/safer CPU temperature and determine whether or not it's the same tone that you're hearing now. If it's not, then your problem must be something else. If it's the same, than I'd suggest re-installing the Heatsink/Fan/TIM (or even going back and installing the original HSF to see if there's any change).
If it is an overheating warning but the Heatsink doesn't feel warm, then its likely a HSF mounting issue - i.e. the CPU IS hot and the heat isn't transferring to the heatsink.
Trying the Supero Doctor III software to monitor voltages/temps would provide more details as well.
reply to daveinpoway
An easier and safer alternative to BIOS editing would be to use a potentiometer to slow down the case fan. Here's one that Zalman includes with a lot of their heatsinks. I've used it a few times and it works pretty well.
reply to Mister_E
The motherboard overheat LED never comes on. I will have to check to see how low I can set the overheat threshold- it is not convenient to shut the PC down to hook up a keyboard and monitor right now.
One confusing thing- I reconnected the rear case fan tachometer wire and the beeping has not returned (so far). If the CPU was overheating, I would expect it to happen all of the time (the CPU workload is pretty constant and the daily report I receive from the software I am running tells me that the CPU usage never goes over 20%).
The software I use on this PC does not allow any other programs (such as Supero Doctor) to be installed, so this monitoring program cannot be easily used.
reply to n_w95482
Yes, I was thinking about one of those speed control potentiometers, but I haven't been able to find any locally. One disadvantage of this approach, however- if the system should overheat, the PWM fan will automatically go to full speed. With the potentiometer, unless someone is around to change the setting, the fan will not be able to attain full speed. This system runs 24/7/365 (even when I am not home), so it needs to be fail-safe.
OK- I'm learning something. Yesterday, I went to Best Buy and bought a Rocketfish 120mm PWM fan (the reviews on this have been mixed, but I can always take it back if the quality is junk). I just shut down the PC (there was no beeping) and replaced the Cooler Master Excaliber rear case fan with the Rocketfish. While things were apart, there was time for the system to cool down (not that it was very warm to begin with).
Immediately upon turning the system back on (before anything could heat up), there was beeping (sometimes the low-pitch beep, sometimes a low pitch which quickly changed to a high pitch). Changing the rear case fan to another motherboard connector had no effect. Looking in the BIOS Hardware Monitor, the Rocketfish seems to run about 100 RPM slower than the Excaliber.
So, it would seem that the beeping is somehow related to the motherboard detecting that the fan speed is slower than it would like to see- heat appears to have nothing to do with it. This would explain why disconnecting the case fan tachometer wire stopped the beeping- if the motherboard did not know that a fan was there, it wouldn't be checking to see if the speed is satisfactory.
As to why this condition has suddenly shown up, I have no clue. There is no place I can see in the BIOS to set a fan speed alarm threshold, so I guess that I will have to leave the case fan tachometer wire disconnected.
Yesterday, when the system was running (no beeps at the time), I used my finger to stop the rear case fan for a few seconds. Sure enough, the alternating high-pitch/low-pitch beeping started immediately. So, even though the Supermicro support rep swore up and down that this beep condition meant local overheating, it is definitely a fan-speed warning.
Perhaps on other Supermicro motherboards (or even on this one with a different version BIOS) the 2-tone beep signifies overheating, but not for my situation.