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#1
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How is fan speed controlled?
Hi all:
I have a Dell Dimension E510 with thermal management issues, It periodically slows down to about 1% of normal speed for several minutes. It has a variable-speed case fan sandwiched between the front of the case and a large heat sink on the CPU. I have spent the better part of two weeks making sure this wasn't a virus, spyware, malware, driver issue, hard disk issue, memory issue, etc. (thanks to several on this NG for their help with that, BTW). I replaced the fan with a new one (Dell pn Y4574), only to find that the problem persists. Coincident with the slowing issue, I noticed that the fan never speeds up beyond "idle" speed, except for a brief second at power-on. Presumably, this is some sort of self-test. It never speeds up again, even when running exhaustive CPU testing algorithms designed to heat it up. Since the new fan exhibits the same symptom, I can only assume it is a temperature sensor somewhere that has failed. Can anyone tell me how this works on a Dell? Can the sensor be replaced, or is it part of the motherboard circuitry? I considered getting an aftermarket fan, but I've read the Dell looks for the presence of the fan and will generate an error if it isn't plugged into it's (proprietary, thanks Dell) connector. It uses a 5- pin connector, but only 4 wires of the pin. The color codes don't match the standard ones, either. My choices, in my order of preference, appear to be as follows: 1: Hot-wire the existing fan to run at full speed all the time. I'd like to try this, just to prove that its a cooling issue and not something else. How? 2: Replace the defective thermal sensor/circuit/whatever. Anybody have a clue where to start? 3: Buy an aftermarket 120mm temperature-controlled fan and jumper the existing motherboard connector to fool the computer. How can it be jumpered out? 4: Buy a new computer. It sure as heck won't be a Dell. FWIW, I tried Dell support, but they were useless. I've been searching for the above information, but I'm either the first person on the planet to have this happen, or no one wants to share what they did, because I can't find it. Thanks in advance, John. |
#2
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How is fan speed controlled?
"the_tool_man" wrote in message ... Hi all: I have a Dell Dimension E510 with thermal management issues, It periodically slows down to about 1% of normal speed for several minutes. It has a variable-speed case fan sandwiched between the front of the case and a large heat sink on the CPU. I have spent the better part of two weeks making sure this wasn't a virus, spyware, malware, driver issue, hard disk issue, memory issue, etc. (thanks to several on this NG for their help with that, BTW). I replaced the fan with a new one (Dell pn Y4574), only to find that the problem persists. Coincident with the slowing issue, I noticed that the fan never speeds up beyond "idle" speed, except for a brief second at power-on. Presumably, this is some sort of self-test. It never speeds up again, even when running exhaustive CPU testing algorithms designed to heat it up. Since the new fan exhibits the same symptom, I can only assume it is a temperature sensor somewhere that has failed. Can anyone tell me how this works on a Dell? Can the sensor be replaced, or is it part of the motherboard circuitry? I considered getting an aftermarket fan, but I've read the Dell looks for the presence of the fan and will generate an error if it isn't plugged into it's (proprietary, thanks Dell) connector. It uses a 5- pin connector, but only 4 wires of the pin. The color codes don't match the standard ones, either. My choices, in my order of preference, appear to be as follows: 1: Hot-wire the existing fan to run at full speed all the time. I'd like to try this, just to prove that its a cooling issue and not something else. How? 2: Replace the defective thermal sensor/circuit/whatever. Anybody have a clue where to start? 3: Buy an aftermarket 120mm temperature-controlled fan and jumper the existing motherboard connector to fool the computer. How can it be jumpered out? 4: Buy a new computer. It sure as heck won't be a Dell. FWIW, I tried Dell support, but they were useless. I've been searching for the above information, but I'm either the first person on the planet to have this happen, or no one wants to share what they did, because I can't find it. Thanks in advance, John. Never had a Dell, but going by my experiences with a recent Asus m/b, I would guess that the fan is controlled by the BIOS working with the CPU's own internal sensor and a m/b sensor. That's why you get full speed for at initial power on, as the BIOS hasn't initialised yet and the fan gets the full 12v. Take a look in your BIOS. |
#3
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How is fan speed controlled?
Somewhere on teh intarwebs Joel wrote:
the_tool_man wrote: FWIW, I tried Dell support, but they were useless. I've been searching for the above information, but I'm either the first person on the planet to have this happen, or no one wants to share what they did, because I can't find it. Thanks in advance, John. Just drag your soul to web store like www.newegg.com then help yourself with information about FAN and FAN Controller. Just need to spend as much time as you need to go through all kind of size's, speed's, noise level, air level, and other options. IOW, all information you need have been around for years waiting for you to gather. You either didn't read the post completely or you failed to comprehend it Joel. John, if I were you I'd be looking for a friend who is into electronics as a hobby who owns a multimeter and can take an educated guess at what the header wires do. You say that you've heard the mobo gives an error if the fan isn't plugged in. You have one right there! You can try it and see. I'm sure for the few seconds required to test, the lack of an idling fan won't hurt your CPU. If you're paranoid you could have the case open and direct another fan toward the heatsink while you do it. Good luck, -- Shaun. "Build a man a fire, and he`ll be warm for a day. Set a man on fire, and he`ll be warm for the rest of his life." Terry Pratchett, Jingo. |
#4
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How is fan speed controlled?
the_tool_man wrote:
Hi all: I have a Dell Dimension E510 with thermal management issues, It periodically slows down to about 1% of normal speed for several minutes. It has a variable-speed case fan sandwiched between the front of the case and a large heat sink on the CPU. I have spent the better part of two weeks making sure this wasn't a virus, spyware, malware, driver issue, hard disk issue, memory issue, etc. (thanks to several on this NG for their help with that, BTW). I replaced the fan with a new one (Dell pn Y4574), only to find that the problem persists. Coincident with the slowing issue, I noticed that the fan never speeds up beyond "idle" speed, except for a brief second at power-on. Presumably, this is some sort of self-test. It never speeds up again, even when running exhaustive CPU testing algorithms designed to heat it up. Since the new fan exhibits the same symptom, I can only assume it is a temperature sensor somewhere that has failed. Can anyone tell me how this works on a Dell? Can the sensor be replaced, or is it part of the motherboard circuitry? I considered getting an aftermarket fan, but I've read the Dell looks for the presence of the fan and will generate an error if it isn't plugged into it's (proprietary, thanks Dell) connector. It uses a 5- pin connector, but only 4 wires of the pin. The color codes don't match the standard ones, either. My choices, in my order of preference, appear to be as follows: 1: Hot-wire the existing fan to run at full speed all the time. I'd like to try this, just to prove that its a cooling issue and not something else. How? 2: Replace the defective thermal sensor/circuit/whatever. Anybody have a clue where to start? 3: Buy an aftermarket 120mm temperature-controlled fan and jumper the existing motherboard connector to fool the computer. How can it be jumpered out? 4: Buy a new computer. It sure as heck won't be a Dell. FWIW, I tried Dell support, but they were useless. I've been searching for the above information, but I'm either the first person on the planet to have this happen, or no one wants to share what they did, because I can't find it. Thanks in advance, John. Based on looking at some descriptions of replacement fans for the Dell, it is a PWM controlled fan. (It would be better for me to get the information straight from Dell, but I don't know if I can confirm my theory that way or not.) http://www.frozencpu.com/products/85...?tl=g36c15s562 Delta Model: AFC1212DE Dell Part Number: D8794 Bearings: 2 Ball Dimensions: 120 x 120 x 38 mm Sensor: TAC yes Connector: 4 Wire, 5 Pin, DELL Airflow: 148.34 CFM Noise: 51 dBA Rated Voltage: 12 V DC at 1.60 A Fan Speed: 3900 RPM As fans go, that is a massive cooling machine, which should sound like a vacuum cleaner when it is wound up to 3900 RPM. Dell apparently wants a very large range of cooling capabilities, by using such a fan. I cannot find a detailed description, but it could be designed similar to an Intel retail fan. Intel fans use a four pin/four wire interface. http://www.formfactors.org/developer...1_2_Public.pdf The speed on an Intel fan, is controlled by a PWM (pulse width modulation) logic signal. The formfactor spec says it is a nominal 5V logic signal. Inside the fan hub, it would need a "logic" MOSFET, with a gate that switches using a 5V signal, to be able to interface and take advantage of a control like that. The choice of 25KHz for the signal, is intended to place the signal above human hearing. That is so the electrical switching, fed into the motor, won't be audible to the user (as a tone). At least, that is my interpretation of the frequency choice. +5V +--------+ +--------+ +--------+ PWM | | | | | high duty cycle. 0V -----+ +---+ +---+ fan goes fast. |--- 40 ---|--- 40 ---| 40 microsecond period = 25KHz +5V +-+ +-+ +-+ PWM | | | | | low duty cycle. 0V -----+ +----------+ +----------+ fan goes slow. +5V +----------------------------------------+ PWM control signal disconnected. Signal floats 0V + to +5V. Fan runs full speed. If a 12V supply is connect to the +12V and GND wires on the fan, with the other two interface signals disconnected, the fan should run at 3900 RPM. There is supposed to be a pullup resistor on the fan circuit board, so that the PWM signal sits at 5V. That indicates a request for 100% speed. Finger chopping time :-) Watch where you stick your fingers, with a fan like that. When the fan controller chip is first started, typically it doesn't drive the PWM, which causes a momentary request to run 100%. Once the BIOS programs the fan controller, the speed drops to a sane level. That may take a second or two. The remaining signal, is a tachometer or it could be a locked rotor signal. Basically, some kind of feedback from the fan, as to what speed it is running at. The computer is interested in whether the fan is functioning at all. (Locked rotor is a logic type signal, which is asserted if the fan cannot spin for some reason.) A tachometer interface on the other hand, pulses twice per revolution of the fan, and the pulsing is related to the commutation and switching of the magnetic field of the brushless DC motor. Seeing a working tacho signal, is how a BIOS can determine a fan is present. The SuperI/O measures the time period, and that is how the BIOS knows what the fan is doing. If the SuperI/O cannot measure the period (because the wire is disconnected), the BIOS will notice. VCC +---+ +---+ +---+ +---+ Tacho signal. | | | | | | | | Speed determined by time 0V +---+ +---------+ +---------+ +---------+ + period measurement. |-- One full revolution --| One rev = two pulses You could try the Speedfan program, from almico.com, and see if it can find a fan speed control. Then experiment to see whether changing the control, makes a difference. Due to the pulsing nature of these signals, it might not be the easiest thing, to draw conclusions using only a multimeter. If you find two pins, that have a full 12V between them, that could be the input power pins. The fan should be fed the full 12V, since the control method is PWM. There is no reason for the motherboard to try to change the voltage. If there is a power track burned on the motherboard, that would be a reason for reduced input voltage. There isn't a good reason for the PWM signal itself to be damaged, because it is just a logic signal. Paul |
#5
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How is fan speed controlled?
Thanks Paul:
That's some very good information. FYI, I've tried SpeedFan, but it does not work with this computer. I've also tried several temperature monitoring utilities, but none find any temperatures on the motherboard. I can use the old fan and a 12V power supply to figure out which wires to use for hot-wiring, but it appears that fooling the bios into thinking the fan is still PWM controlled won't be doable. I may try misfit's advice and unplug the fan from the motherboard, just to see what happens. If I just have to hit F1 at bootup or something, I can live with that. Thanks again. Regards, John. |
#6
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How is fan speed controlled?
the_tool_man wrote:
Thanks Paul: That's some very good information. FYI, I've tried SpeedFan, but it does not work with this computer. I've also tried several temperature monitoring utilities, but none find any temperatures on the motherboard. I can use the old fan and a 12V power supply to figure out which wires to use for hot-wiring, but it appears that fooling the bios into thinking the fan is still PWM controlled won't be doable. I may try misfit's advice and unplug the fan from the motherboard, just to see what happens. If I just have to hit F1 at bootup or something, I can live with that. Thanks again. Regards, John. Connecting +12V and GND, should make the fan run full speed. (As long as the open-circuited PWM control signal on the fan, has an internal pullup resistor.) Connecting the tacho signal, which pulses twice per revolution, would be what the BIOS is monitoring. Some people have even taken the tacho signal from another running fan, and offered that signal as a means to keep a BIOS happy. But your nonstandard (5 pin) connector, is going to make rigging that up, a bit of a nuisance. The PWM signal travels from computer to fan, and the computer doesn't really care whether the signal is loaded by an electrical load or not. It wouldn't typically monitor that signal. And the setup would not be "applying a little PWM", then "looking at tacho" for a response. They don't usually try to run the thing closed-loop, looking for a speed increase, when PWM is cranked up. With regard to SpeedFan, have a look at the motherboard. I thought I saw an SMSC SuperI/O chip in a picture of the motherboard, and that could be what the board is using for a hardware monitor. SpeedFan searches particular addresses on the low speed buses, looking for chips like that. Sometimes, with these hardware monitor programs, it is necessary to use some obscure option (like a different address), to get the SuperI/O recognized. Another program you could try, would be Motherboard Monitor. It doesn't control the fan, but you may be able to determine whether the hardware interface can be detected or not by that program. Unfortunately, this web site is now gone, and when I checked web.archive.org, the site was blocked by a norobots.txt file, so the site didn't get archived. So we cannot see whether your computer would have been supported. http://mbm.livewiredev.com (site is dead) http://majorgeeks.com/download.php?det=311 (file still available) Even this, might be used to detect the SuperI/O hardware monitor. It really depends on the history of this tool, like where its detection code comes from, as to whether it will have good coverage for all equipment or not. http://www.cpuid.com/hwmonitor.php Paul |
#7
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How is fan speed controlled?
On Apr 20, 8:42*am, Paul wrote:
Connecting +12V and GND, should make the fan run full speed. (As long as the open-circuited PWM control signal on the fan, has an internal pullup resistor.) Connecting the tacho signal, which pulses twice per revolution, would be what the BIOS is monitoring. Some people have even taken the tacho signal from another running fan, and offered that signal as a means to keep a BIOS happy. But your nonstandard (5 pin) connector, is going to make rigging that up, a bit of a nuisance. The PWM signal travels from computer to fan, and the computer doesn't really care whether the signal is loaded by an electrical load or not. It wouldn't typically monitor that signal. And the setup would not be "applying a little PWM", then "looking at tacho" for a response. They don't usually try to run the thing closed-loop, looking for a speed increase, when PWM is cranked up. With regard to SpeedFan, have a look at the motherboard. I thought I saw an SMSC SuperI/O chip in a picture of the motherboard, and that could be what the board is using for a hardware monitor. SpeedFan searches particular addresses on the low speed buses, looking for chips like that. Sometimes, with these hardware monitor programs, it is necessary to use some obscure option (like a different address), to get the SuperI/O recognized. Another program you could try, would be Motherboard Monitor. It doesn't control the fan, but you may be able to determine whether the hardware interface can be detected or not by that program. Unfortunately, this web site is now gone, and when I checked web.archive.org, the site was blocked by a norobots.txt file, so the site didn't get archived. So we cannot see whether your computer would have been supported. http://mbm.livewiredev.com* (site is dead) http://majorgeeks.com/download.php?det=311* * (file still available) Even this, might be used to detect the SuperI/O hardware monitor. It really depends on the history of this tool, like where its detection code comes from, as to whether it will have good coverage for all equipment or not. http://www.cpuid.com/hwmonitor.php * * Paul Once again, lots of good info. I figured the fan wasn't closed loop, but it's nice to get confirmation. I've not been able to get either SpeedFan or MBM to work with my system. Also, the BIOS has no provision for altering the fan speed, or anything else relative to cooling. If everything you have said is true, then if I figure out which wire is the PWM signal to the fan, I should be able to cut that one wire (or pull it from the connector), and the fan will run at full speed all the time, right? The fan gets 12V & GND, the PC gets a pulse train. Everybody's happy. The only downside is the fan noise. Still, that might get me by. I'll experiment as soon as I can and let you know what I find out. Regards, John. |
#8
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How is fan speed controlled?
On Apr 20, 9:40*am, Joel wrote:
* * * * The other option is to set the fan speed in CMOS setting. *And you you PLEASE quote some original text to lets other know which message you respond to. *And if you will then please DO NOT top-posting else you will end up in my kill-file Joel: So far, you've suggested doing a bunch of things that I've already done, implying I'm too lazy to pick out my own aftermarket fan. Did you even read my post? That's not what I was asking. Now, you're telling me how to use Usenet. So far, based upon your contribution to resolving the issue (zero), I think adding me to your killfile would probably be the best thing for both of us. Have a nice day! John. |
#9
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How is fan speed controlled?
On Mon, 20 Apr 2009 14:58:33 -0700 (PDT), the_tool_man
wrote: Even this, might be used to detect the SuperI/O hardware monitor. It really depends on the history of this tool, like where its detection code comes from, as to whether it will have good coverage for all equipment or not. http://www.cpuid.com/hwmonitor.php * * Paul Once again, lots of good info. I figured the fan wasn't closed loop, but it's nice to get confirmation. I've not been able to get either SpeedFan or MBM to work with my system. Also, the BIOS has no provision for altering the fan speed, or anything else relative to cooling. What about HWMonitor (linked above)? Try running a CPU speed detection program like CPU-Z when the slowdown occurs. http://www.cpuid.com/cpuz.php You might be able to force a higher thermal level by running Prime95's Stress Test. The point is, I am not seeing a clear poof the CPU is overheating to the point where it would throttle down to a lower speed, and if it did throttle down it should not be so slow as 1% of the original speed. Since you can't get a temp reading, you might try touch-testing the heatsink to see how hot it feels. If it is hot enough to effect CPU function it should be uncomfortable to leave your finger on for more than a couple seconds, unless the heatsink itself has someone become partially detached and CPU overheats due to poor thermal interface that resulted. |
#10
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How is fan speed controlled?
the_tool_man wrote:
Once again, lots of good info. I figured the fan wasn't closed loop, but it's nice to get confirmation. I've not been able to get either SpeedFan or MBM to work with my system. Also, the BIOS has no provision for altering the fan speed, or anything else relative to cooling. If everything you have said is true, then if I figure out which wire is the PWM signal to the fan, I should be able to cut that one wire (or pull it from the connector), and the fan will run at full speed all the time, right? The fan gets 12V & GND, the PC gets a pulse train. Everybody's happy. The only downside is the fan noise. Still, that might get me by. I'll experiment as soon as I can and let you know what I find out. Regards, John. http://www.fatwallet.com/forums/computers/787381 "The 5-pin fan has 4 wires (black, white, red, and blue) and the 3-pin fan has 3 wires (black, white, and red). Can I make the 5-pin (but strangely 4-wire) fan work with my 3-pin motherboard? I've already spliced the wires and plugs and matched up the red, black, and white wires. This makes the fan "work", but doesn't seem to allow for any regulation of the fan's speed (it's at jet engine speed at all times, which is quite loud). I suspect that the blue wire is somehow involved in speed regulation, but am not sure what to connect it to. Anybody know if I can double it up with one of the other 3 wires, or is the regulation mechanism different such that they're not directly compatible? Thanks! " So that sounds like a description of leaving the PWM signal open circuit, causing the fan to run like a "jet engine". It suggests red = +12V, black = GND (those are common color choices for wiring, with red being a positive supply, black being ground). The guy wired white as RPM. And left the blue open circuit. I tried searching elsewhere, for pinout info, but wasn't successful. That is as close as I got. There are a couple sources of "Dell 5-pin to standard 4-pin" adapters, but the cabling was sleeved to hide the details. One of those would allow working backwards, to get the Dell pinout. I'm still puzzled by the control method, as I would have expected *some* utility to have detected the fan controller chip. Paul |
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