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#1
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Annoying fan speed problem
Hi
I have an AMD64/ASUS K8N-E deluxe based system with a non-AMD cpu fan (and hence slower, quiter fan). I have problems with the BIOS shutting down the system shortly after a cold reboot. Turns out that the BIOS is hardcoded to belive that any fan speed below 1800 rpm means there is a problem. My new fan runs at 1200 rpm at boot time, which makes the BIOS shut down the system after a few minutes. OK, some months ago I "fixed" that (with good help from people in this NG) by disabling the fan speed monitor in the BIOS. This *used* to work OK, until recently when - for no apparent reason - the BIOS seems to belive that either the "Ingnore fan speed" option in itself or the 1300 rpms of the fan is again good reason to shut down the system. My options seems to be: 1. Use the standard AMD supplied fan 2. Change the MB 3. Somehow make the MB belive the fan runs at a higher speed that it really does... 4. Accept a number of shutdowns/reboots ... I like alternative 3 best. Does anyone know how a fan reports it's speed to the MB? Would it just report the voltage across the fan? Or somehow the actual fan frequency/rpm? Or... ? Thanks |
#2
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Annoying fan speed problem
Peter wrote:
Hi I have an AMD64/ASUS K8N-E deluxe based system with a non-AMD cpu fan (and hence slower, quiter fan). I have problems with the BIOS shutting down the system shortly after a cold reboot. Turns out that the BIOS is hardcoded to belive that any fan speed below 1800 rpm means there is a problem. My new fan runs at 1200 rpm at boot time, which makes the BIOS shut down the system after a few minutes. OK, some months ago I "fixed" that (with good help from people in this NG) by disabling the fan speed monitor in the BIOS. This *used* to work OK, until recently when - for no apparent reason - the BIOS seems to belive that either the "Ingnore fan speed" option in itself or the 1300 rpms of the fan is again good reason to shut down the system. My options seems to be: 1. Use the standard AMD supplied fan 2. Change the MB 3. Somehow make the MB belive the fan runs at a higher speed that it really does... 4. Accept a number of shutdowns/reboots ... I like alternative 3 best. Does anyone know how a fan reports it's speed to the MB? Would it just report the voltage across the fan? Or somehow the actual fan frequency/rpm? Or... ? Thanks Hi, I don't have an answer for your problem, but I think fan speed is typically reported to the MB via a 3rd wire from the fan, which has a "pulse" or "clock" type output as the fan spins, so it's not just a voltage. Jim |
#3
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Annoying fan speed problem
OK, thanks; that would mean I would need to have a device - on that
wire - that could double that clock speed. Hmm, need to think about that one. Many thanks! |
#4
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Annoying fan speed problem
On 21 May 2006 06:08:25 -0700, "Peter" wrote:
OK, thanks; that would mean I would need to have a device - on that wire - that could double that clock speed. Hmm, need to think about that one. If you think the fan is good, swap cpu and system fan connections. |
#5
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Annoying fan speed problem
"Peter" wrote:
OK, thanks; that would mean I would need to have a device - on that wire - that could double that clock speed. Hmm, need to think about that one. A crude (mechanical) device could be made from a dummy fan with the blades removed - it would spin fast enough to satisfy the board, but wouldn't make (hardly any) noise. A more elegant approach could be made from something like a 555 timer in astable mode (depending upon the voltages required by the tach sensor, of course). Jon |
#6
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Annoying fan speed problem
Jon Danniken wrote: "Peter" wrote: OK, thanks; that would mean I would need to have a device - on that wire - that could double that clock speed. Hmm, need to think about that one. A crude (mechanical) device could be made from a dummy fan with the blades removed - it would spin fast enough to satisfy the board, but wouldn't make (hardly any) noise. A more elegant approach could be made from something like a 555 timer in astable mode (depending upon the voltages required by the tach sensor, of course). Jon Many thanks! |
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