[dtweleve]

First time on this forum and I have posted this problem on other PC hardware forums but without any replies.

I'm looking for an explanation for the behaviour of my Compaq Presario desktop fans (CPU, Case, and PSU):

Processor Intel Pentium 4 2000 MHz
CPU Clock 1994.2 MHz (20.0 x 99.7 MHz QDR)
Chipset 82845MP Brookdale Host-Hub Interface Bridge (B0-step)
Mobo Compaq Computer Corporation
Graphics nVidia FX 5200
PSU 250W

The problem that SOMETIMES and after my child plays a game such as WoW on the desktop, the fans remain at higher than usual speed (22% to 44% as reported by SpeedFan) even though the CPU is mainly at idle and the CPU temperature is lower than 40 C. The fans would remain at that speed until the desktop is restarted or put on standby or reduced to 0 by SpeedFan.

I have done the following so far:

1. Fresh install of XP Pro plus all required updates although I do not believe this is a software problem. I just wanted to eliminate the s/w part.

2. Removed and cleaned the CPU fan, removed and cleaned the thermal grease and then applied a uniform thin layer of RS Heat Sink Compound. This actually improved the overall operation of the desktop where it's quiet most of the time.

3. The case as well as its fan along with the PSU fan have always been clean. As a matter of fact, the case fan has been replaced a while ago since it was making unusal noise at certain speed.

4. I restored the original BIOS and it did not make any difference. So, reverted to the updated version. By the way, there are no parameters associated with fans or temps in this computer BIOS.

Overall, the desktop is performing well although I do not use any heavy applications or games. The CPU normally and most of the time controls the speed of the fans under certain heavy loads and it then drives them to the minimum speed when it's not busy. However, under certain conditions, those fans would get stuck at a certain speed and the CPU no longer controls them while it's idling and, therefore, it should drive the speed of the fans to minimum (0 as would be reported by SpeedFan). As I said, the CPU with 96-98% idle and no apps running and at low temperature of 40 C or below.

What could cause those fans to remain at that higher speed? Why can the CPU not drive them to minimum idle speed?

Your feedback would be appreciated. Thank you in advance.

 

[dtweleve]

Hello Everyone in this forum, I was hoping to get some feedback from you regarding this issue with my desktop. Please share your thoughts and ideas. Thank you.

 

[Doby]

Hi dtweleve,

We are not ignoring you I promise, I have read your thread 3 times and I just think what it would be because there are no options in bios to controll the fan speeds, still bios must be controlling the fans????????

What model Presario is it? I'll have a look around.

Your using speedfan, uncheck the box "automatic fan speed" and see what happens maybe there is some sorta interferance

 

[dtweleve]

Hello Doby,

I appreciate your feedback on this issue. My desktop is Presario 6078EA. As a matter of fact, the box "automatic fan speed" was never checked and SpeedFan starts manually when I decide to run it to check the status of the temps and the fan speed.

Could it be the ADM1028 on SMBus (detected by SpeedFan) that reports invalid info to the CPU which in turn thinks the fans should be at higher speed when they should not?

I've been searching the web for some info on how the CPU controls the fans and I have no success yet to understand why my CPU tends to forget the fans spinning when there's no need for them because the CPU temp is low (40 C or below) and ther's no load on the CPU (mainly idle).

 

[dtweleve]

Hi Doby,

I have located the Data Sheet of ADM1028 here :

http://www.analog.com/UploadedFiles/Data_Sheets/ADM1028.pdf

and it's clear that ADM1028 is the one that controls the fans of the desktop depending on the input of the temp sensors (ambient & remote - CPU) on the mobo. The ADM1028 is setup completely by various registers which as you said must be initialized by the BIOS. The Data Sheets states the following in the FAN SPEED RAMPING section (page 10):

FAN SPEED RAMPING
The ADM1028 device contains a Fan Speed Ramping mechanism that is accomplished using an 8-bit counter and a control register. On power-up, or an assertion of RST or AUXRST, the Fan Speed Register, counter, and Fan Speed Ramp Register are
initialized to 0x00. The fan speed ramping mechanism is disabled by default and any value written to the Fan Speed Register is immediately reflected on the FAN_SPD output. Setting Bit 0 of the Fan Speed Ramp Rate Register enables the ramping mechanism. The counter is then preloaded with the current value contained in the Fan Speed Register, which prevents the fan speed from changing until a new value is written to the Fan Speed Register.

And I would refer to the last statement " Setting Bit 0 of the Fan Speed Ramp Rate Register enables the ramping mechanism. The counter is then preloaded with the current value contained in the Fan Speed Register, which prevents the fan speed from changing until a new value is written to the Fan Speed Register."

Perhaps and somehow the register is not updated under the conditions that the fans of my desktop keep spinning at a certain speed.

Regards

 

[dtweleve]

Hello Everyone,

I have captured the state of the desktop while ALL the fans were ON with the CPU at idle and at low temperatures. I have attached this desktop state as captured by SpeedFan. There's a lot of information in this report and I personally can not analyze it due to lack of knowledge of all the listed parameters. Perhaps, some viewers of this Forum as well as the Support Team can share their thoughts and ideas regarding this information which might explain the state of the desktop.

1. Could it be a hardware fault, perhaps but what could drive the fans that way beside ADM1028?

2. Could it be a design fault, perhaps but I could not find any information on the web related to this model?

Mind you this issue could have existed since the beginning when I purchased the desktop in 2002 but it was not noticed earlier mainly because no activities triggered those conditions. Even if they were triggered, I probably always restarted the desktop to reset the fans speed. I also thought at certain times that the fans were driven that way because of certain software installation by the kids. However, and as I mentioned earlier, that I decided recently to clean up the desktop (software & hardware) in order to assess the operation. That’s the reason I decided to re-install windows to start with fresh operation.

Please share your views to help understand this issue. Thank you.

 

[dtweleve]

Hello Everyone,
I think I have resolved this issue but I have to wait for few days with the desktop running and being exercised to confirm. I'll keep you posted. Regards.

 

[dtweleve]

Hi Everyone,

I thought I solved this problem by replacing the IDE cable but the fans got stuck again three days later. I'm hoping that the support team who promised over two weeks ago to share their knowledge regarding this issue.

I wonder if someone could tell me how I can edit an attached to my previous post. I could not find any tool to edit the attachment so I can make some changes. Is it possible?

 

[Doby]

The edit button only appears for 30 minutes or so after your post, you then have to reply again.

I am sorry I don't have any other suggestions on why it is doing that

 

[dtweleve]

Doby,
Thank you for your reply. As a TSF member, you probably have an administrator privilage. If so, could you please delete the attachment of my post on Dec 14 of this thread and then I attach an updated one. Thank you in advance.

 

[Doby]

Deleted the attachment on post #6 as requested