TLDR: A particular fan does not obey bios speed settings on the CPU header despite fact it does work on secondary chassis header, (fan isn't defective). The CPU header itself is fully functional however because both the stock fan and a third fan do obey bios speed settings applied via that header.
As the title implies, the stock intel cooler works as normal wherein it obeys the auto or custom (manual) duty cycle fan speed setting set in BIOS, associated with CPU 4pin header.
But when I try an aftermarket cooler fan, 4pin type, it ignores the settings in bios and instead runs at max RPM.
I see this problem mentioned on two other message boards on the web and so it seems to be a recurrent theme / specific with Intel Desktop boards, regardless of aftermarket cooler model/brand.
FWIW I have troubleshooted the AM fan to ensure it isn't defective. I put the fan on the alternative Chassis Header - on the same motherboard and adjusted the setting associated with that header in BIOS, in such config, the fan does honor the setting.
So what gives intel? why do Intel Desktop boards discriminate against Aftermarket coolers inserted in the CPU header but not their own stock cooler?
The aftermarket cooler runs at max, 3000RPM and is just too loud.
I need the system header for other fans.
FYI: I have updated BIOS to latest to no avail.
What is the model number of your Intel Desktop Board?
"So what gives intel? why do Intel Desktop boards discriminate against Aftermarket coolers inserted in the CPU header but not their own stock cooler?"
Are you serious? Have you considered that Intel's quality control and tolerances are simply better than aftermarket?
No matter - all the desktop boards have been discontinued and no longer supported.
the board is DH77DF although as I say, there are other people as far back as 2007 who had a similar probs with other boards (and no solution has ever been found).
I understand desktops boards are unsupported as they have progressed onto NUC. I can work around this problem but I am curious to know of perhaps any suggestions.
The chassis header allows manual adjustment of both Intel and AM fan, wheras the CPU header setting only controls Intel stock alone.
Its peculiar that the fan obeys one header and not the other, right?
One could argue that because the fan is 3000RPM, even the minimum PWM duty cycle does not affect the speed (stock cooler is 2000RPM max).
But that still does not explain the discrepancy of behaviour between headers. Why would one header have different electrical characteristics to the next?
So let me point a few things out about the fan speed control capability of the DF board:
A. 4-Wire fans vs. 3-Wire fans:
- The 4-Wire fans chosen should be compliant with the 4-Wire PWM Fan specification. Proper operation is NOT guaranteed (perhaps always full speed?) for 4-Wire fans that are not compliant with this specification.
- 4-Wire fans are provided with constant 12V power and they themselves implement how the PWM signal's duty cycle will be interpreted into an actual fan speed.
- How 4-Wire fans react to duty cycle values below 20% is undefined. They could stay at the 20% duty cycle speed, they could turn off or they could do something in-between. In some cases, the noise generated by a fan in this "in-between" response can actually be louder or inconsistent (warble, etc.) as the fan struggles not to stall. This can also be damaging to the fan. It is thus recommended that you not use a Minimum Duty Cycle setting below 20%.
- 3-Wire fans are controlled using voltage variance. That is, the duty cycle will specify the power voltage (0-12V) that is supplied to the fan.
- 3-Wire fan design can vary and thus how they react to the power voltage can vary as well.
- All fans report their rotational speed via pulses on the tachometer signal. Most (alas not all) fans generate two tachometer pulses per revolution. The fan monitoring circuits on this board presume that they get two tachometer pulses per revolution. If the fan actually generates more or less pulses per revolution, the fan speed will be incorrectly reported.
B. CPU Fan Header:
- The CPU Fan header properly supports only 4-wire PWM fans that are fully compliant with the 4-Wire PWM Fan specification.
- If you plug a 3-wire fan onto the CPU Fan header, it will always run at full speed.
- I have a 3rd-party low-profile CPU heatsink-fan unit that is compliant with the 4-Wire PWM Fan specification and it works just great on the CPU Fan header of the DF boards.
C. System Fan Header:
- Has the ability to recognize and use both 4-wire and 3-wire fans.
- 4-Wire fans that are compliant with the 4-Wire PWM Fan specification - which specifically have the requisite pull-up on the Tachometer signal wire - will be recognized and controlled using the PWM signal. All other fans will be controlled using voltage variance control.
- Whether specific non-compliant 4-wire fans will respond well to being controlled using voltage variance is an unknown (who knows what they have done wrong in their designs).
- Because the DH77DF board shares a BIOS with the DH77KC board, Visual BIOS will incorrectly show tabs for Front and Rear fans. The Front fan tab is what you use to configure the DH77DF board's System fan. The Rear fan tab is ignored (only supported when the DH77KC board is present).
D. Fan Response Programming
- The Control Mode parameter, if set to Manual, causes the fan to be operated at the setting specified by the Manual Duty Cycle parameter.
- The Control Mode parameter, if set to Auto, causes the fan to be operated between the Minimum Duty Cycle parameter setting and the Maximum Duty Cycle parameter setting.
E. Temperature Response Programming
- The Control Temperature parameter specifies the upper limit on the fan control temperature range. That is, the temperature where the fan response reaches the maximum duty cycle (typically 100%).
- A fixed 15-degree temperature range is used for fan speed control. That is, from Control Temperature -15 up to Control Temperature, the fan will be taken from its Minimum Duty Cycle parameter setting to its Maximum Duty Cycle parameter setting.
- The Responsiveness parameter specifies the shape of the response "curve". It is explained in the diagram below.
- The Damping parameter specifies how quickly the circuit will respond to changes in temperature. The difference is very subtle and difficult to distinguish, since it happens over time, so don't waste a lot of time trying to distinguish the difference (pun intended).
- The All-On Temperature parameter specifies the temperature at which the fan will be taken to 100% duty cycle regardless of the setting of the Maximum Duty Cycle parameter for the fan (i.e. this is an override).
- The Over-Temperature Threshold parameter is used for health determination and does not affect fan speed control.
Ok, that should be enough information for you to properly determine what is and isn't working. As I said, I have a DH77DF and both fan headers are working properly.
Ok thanks for the incredibly detailed answer Scott.
I know the diff. between DC and PWM control.
The Akasa Fan may not be to spec but the company seems reputable.
I only recently purchased the board 2d hand - Is it possible that previous owner potentially damaged the header, i.e. electrical short?
Remember: I tried adjusting manual duty cycle under CPU tab, and like I say, that doesn't slow the fan regardless of setting.
I figured out the diff. between Front and Rear tabs, the latter is irrelevant true.
I shall test more with the temp tab however, in default config I see no reason why Akasa fan runs at full ab initio. I tested a Gelid cooler and it runs quiet much like the stock Intel cooler does.
Under full load in target scenario, the stock cooler, runs at 1000RPM and the CPU does not exceed 56deg. I noted that one is designed to dissipate upto 73w. This is the same spec for the Akasa.
Thanks again I'll report back in 24hours, gotta sleep.
Ok, @gsere4, you confused me there.
Are you saying that the CPU Fan header is working properly with the boxed CPU heatsink-fan unit AND the Gelid cooler, BUT NOT with the Akasa low-profile heatsink-fan unit?
Or are you saying that there appears to be a problem with any 4-Wire fan plugged into the CPU Fan header?
If the problem is isolated to the Akasa low-profile heatsink-fan unit, then you likely have a bad fan from Akasa. I would get them to replace it. If the problem appears to be the fan header, then you need to decide whether to reject this (used) board.
Sorry for confusion!
Back to basics
I reverted bios to defaults and I tried all three fans again on the CPU header; stock and gelid fans do respect both manual and auto duty range settings but the akasa does not.
Despite the akasa not working on CPU header fan, the akasa fan does obey lower Duty cycle associated with the Chassis fan header when it is plugged into that. Isn't that weird?
So, the fan isn't defective because it works on the chassis header while simultaneously not working on the CPU header fan when plugged into that. + the cpu header can controll the stock and the gelid but not the akasa cooler. 😬😁 😬😁😬😁
The specs of the Akasa
Intel LGA775 , LGA115X
Cooler dimension 87.2 x 85.2 x 29.5 mm
Heatsink material Aluminum with copper insert
Weight 220 g
Installation Push pins
Fan dimension ∅74 x 15 mm
Fan speed 600 - 3000 RPM (PWM controlled)
Max airflow 33.50 CFM
Max air pressure 3.76 mmH2O
Noise level 28.71 dB(A)
Voltage rating 12V DC
Bearing type HDB
Fan life expectancy 50,000 hours
Fan connector 4pin PWM
Product code AK-CC7118HP01
Current Rating: Unknown
Air Flow (CFM/CMH): max. 20
Bearing: Ball Bearing
Cable Length (mm): 250
Current (A): 0.2
DC Voltage (V): 12
Fan Dimensions (mm): 65 (dia) x 15 (h)
Fan Speed (+/- 10% ) (RPM): 1200 – 2600
Heat Sink with Fan Dimensions (mm): 105 (l) x 74.5 (w) x 28 (h)
Life time MTTF at 40C (h): 50’000
Noise Level (dBA): 15 – 27.2
Static Pressure (mmAq): 1.25
Warranty (years): 5
Weight (g): 282
The Akasa fan *is* defective. As I detailed earlier, if you connect a 4-wire PWM fan to a Chassis fan header but this fan is not properly recognized (at power on; do not change fans on the fly) as being a 4-wire PWM fan, it will be controlled using voltage variance and thus could appear to be working properly when, in fact, it is not.
You can verify this using a meter to check the voltage on pin 2. If it is using PWM control, you will see a solid 12V on this pin. Otherwise, you can see a varying voltage.
No, the Chassis Fan header supports both 3-wire and 4-wire fans. At power on, the type of fan connected is detected. If it is a compliant 4-wire fan, then the header provides a constant 12V of power to the fan and the fan uses the PWM signal to determine how fast it should spin. For all other fans (i.e. 3-wire and non-compliant 4-wire), the PWM signal is used locally on the motherboard to determine the voltage to send to the fan (0% = 0V up to 100% = 12V).
A quick summary of fan pinouts is here: https://allpinouts.org/pinouts/connectors/motherboards/motherboard-cpu-4-pin-fan/.