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Thread: GA-MA790GP-DS4H Sys Fan control




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    Default GA-MA790GP-DS4H Sys Fan control

    Since I don't always use Windows as an OS, I was hoping that the BIOS control of the Sys Fan speed would be good.

    It isn't - on Auto it simply sits at a low level and never moves. Obviously an oversight.

    Perhaps in a later BIOS release the operation of the SYS Fan could be improved/fixed? Would make a big difference - this is not a cheap board!

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    Default Re: GA-MA790GP-DS4H Sys Fan control

    ON Auto it should speed up once heat increases, did you test this under load?

    Hey, you do not have Auto as a Choice for System fan >>>

    System Smart FAN Control

    Enables or disables the system fan speed control function. Enabled allows the system fan to run at different speed according to the system temperature. You can adjust the fan speed with EasyTune based on system requirements. If disabled, system fan runs at full speed. (Default: Enabled)

    So you can set to enabled and control it with EasyTune, but that also likely depends on what type of fan it is as well. If it is not a 4Pin then you may not be able to adjust it

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    Default Re: GA-MA790GP-DS4H Sys Fan control

    It is Enabled (I said Auto in error). It runs at 750 rpm (full speed is 1250rpm). It never increases whatever the load - the CPU fan acts correctly.

    It is 3 pin - I've never seen a 4 pin (PWM) case fan in the 20 years I've been building and modding PCs.

    The fact that the fan runs at 750rpm infers that the DC voltage is around 8V and this is borne out of a measurement with a DMM/DVM. So there is some control, albeit static... and not PWM either.

    I'm currently using a Zener diode in each case fan lead to spin the fans at about 3/4 speed. This is overly fast for low loads, and too slow when data crunching.

    I don't just use Windows, so Easytune is not an option, nor would I like to use in reality, the MoBo is not a budget item and the feature advertised should work.
    Last edited by LanceH; 01-10-2009 at 02:15 AM.


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    Default Re: GA-MA790GP-DS4H Sys Fan control

    Ahh ok, well are you sure? I mean about the load, did you run orthos on it and see? Well I guess Overall system/case temps would likely need to be increased for it to go faster.

    Yes, there is Plenty of 4Pin Case fans, which is why you see sys_fan2 has a 4pin header. Which Sys_Fan header are you using by the way? If 2, try 1 as I see many issues on various boards with Sys_Fan2. Here are some 4Pin PWM Case fans, so you know I am not crazy >>>
    Newegg.com - PWM, Case Fan, Case Fans, Fans & Heatsinks, Computer Hardware

    Here is what a member here has found thru testing for each fan >>>
    CPU_FAN connector needs a CPU cooler with four wires were the PWM modulator is included in the cooler. The mobo senses the CPU temperature and managing the pin 4 signal, the cooler's fan will automatically be increased or decreased, following the CPU temp. Fan's rotation feedback returns via pin 3 for BIOS alarm feature.

    SYS_FAN2 connector needs any fan, with three or four wires (don't care) since the speed is controlled via on-board PWM controller that supply pulse-width-modulated 12v for the fan via pin 2. So, if using a four wire fan, its internal PWM is locked to full speed (this explain that fixed 5v on pin 4). This time, the mobo senses the North Bridge (in my case the P35) temperature and will increase or decrease the speed of the fan connected in this socket. Feedback is sent to pin 3 for BIOS alarm purposes.

    SYS_FAN1 and PWR_FAN are three pin socket with fixed full speed fan. No controlled rotation at all from the mobo. Rotation feedback also monitored via pin 3 only for BIOS alarm purpose.

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    Default Re: GA-MA790GP-DS4H Sys Fan control

    On this board, the 4 pin header is SYS FAN 1, not 2. Yes, I did a burn-in on the MoBo with the 9950BE and noted the inactivity of the fan speed. 100% CPU load for several hours. I don't know where the sensor is for the SYS FAN, but it is neither close to the NB or the VRMs - unless GB like allowing the VRMs to get to 70 deg!

    Thanks for the Newegg link - however, there are ONLY 3 120mm fans there and none of those are sold in the UK. As I said, 4 pin case fans are effectively non-existant. And as I stated above, the SYS FAN header is controlling the DC supply to the fans - it just doesn't adjust it. That is, in other words, a BIOS fault. Or feature.


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    Default Re: GA-MA790GP-DS4H Sys Fan control

    Yes VRM's can get very hot, I have seen them 90-100 on some boards

    Ya, There is only a few at newegg, I just linked that to show you they are made for sure.

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    Default Re: GA-MA790GP-DS4H Sys Fan control

    I have been corresponding with Gigabyte technical. Basically, they simply don't understand what I'm on about, and have little inclination to accept it as an issue. Despite this being a fairly high spec board (and not cheap).

    Firstly, 4 pin Case fans are virtually unobtainable. However, this doesn't actually matter - the 4 pin header DOES control the fan by varying the DC voltage, so 3 pin fans are fine. But, the SYS FAN control uses a temp sensor located a million miles from a source of increasing heat with load. So it never actually increases fan speed because it won't sense a rising temperature. On this board, the NB temperature stays at about 31C whatever the load. If I gently play a hairdryer toward the NB, the fan speed increases as you would expect.

    It would be dead easy to correct this - simply amend the BIOS to use a different sensor to then control the fan - VRM temp would be ideal. Failing that, do what ASUS QFan2 does and use the CPU temp.... not ideal, but better than this.

    For anyone else with Intel or AMD Gigabyte boards expecting the 4 pin SYS Fan control to work, don't.


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