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Vostro 430 design fault on Temperature Sensor causing excessive cooling and noise

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Vostro 430 design fault on Temperature Sensor causing excessive cooling and noise

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I have just got one of the new Vostro 430's with a Core i7 860.

When the machine first boots up, the fans spin upto full speed, which is loud but ok, as once Windows loads, the fans drop to their idle state which is 1500rpm. I'm one of these people who leaves their PC on 24x7. Anyway, during the night, I can hear the PC noise increasing considerably and after a few days it's becoming unbearable.

After investigating i've discovered a design fault with the temperature sensor under to CPU socket.

When the PC is not under load and using HWMONITOR, the power usage of the CPU drops to about 24W and the fan speed is 1500rpm. The sensor TMPIN0 will eventually drop to 0c, when this happens the fan speeds increase to 4500rpm for the CPU fan and 2400rpm for the case fan which generates an excessive amount of noise. It will take a while for the sensor to drop to 0c, but once it does happen, the excessive cooling causes the sensor to drop to -2c and therefore the problem with the noise will not stop.

During the day the sensor will go above 0c and when that happens the fan speed drops back to 1500rpm for the CPU and 1200rpm for the case fan, which is quiet.

I have also noticed that the temperature sensor under the CPU socket also fluctuates a lot, going from 5c to 16c in a second and back again, so the problem could be any of the following :

  1. The Sensor is not calibrated properly, perhaps a BIOS update could fix this ?
  2. Assuming the bios is controlling the fan, why does it allow the fan to spin upto 100% if the temperature is already cold ? Perhaps a BIOS update could fix this ?
  3. The sensor itself is defective

Solutions attempted so far :

  1. Updated BIOS to 1.0.2, did not work
  2. Dell engineer replaced motherboard, did not work
  3. Shut down PC, allow the heat in the room to rise, restart PC, fixed until the motherboard sensor cools to 0c
  4. Download a copy of Super PI (to load the CPU), CPU usage increases to 12% or so, the sensor immediately increases to 20c, power usage increases to 115W, and Fan speeds drop to their idle levels 1500 and 1200rpm. This would seem to indicate that the issue has something to do with the power usage and/or the CPU generating more heat. However the the temperature should not just jump from 0c to 20c instantly.

A little background about myself, IT Consultant building PC's for 20 years since the old 286 / 386.

 

All Replies
  • I too have just taken delivery of a Vostro 430 running Windows 7 and have exactly the same problem. When I turn the computer on the fan starts up at full speed and then periodically turns on and off.

    Now, more by luck than good judgement, I rebotted the computer and pressed F2 to get into the BIOS. I wanted to see if there was anything that may affect this fan speed. Just by luck I turned off the "NUM LOCK" setting and pressed the Save to exit and continue the reboot. Much to my surprise the fan did not ever go back up to full speed. The following day, the same thing happened again. When the computer first started up the fan was doing the same thing again, periodically full speed and off. So I rebooted and again went into the BIOS with F2 and this time just did a save without changing anything. Lo and behold, the fan has now stoppped this on/off behaviour. More tests will continue as to whether this is a real fix and the exact sequence of events required.

    My BIOS version is still at V1.0.1

  • What I have discovered is that the issue only occurrs if you have very low CPU usage and the speedstep kicks in to lower the power usage (24W).  When the issue occurrs, if I run SuperPI to force the CPU to max speed (115w power usage), the problem stops immediately.

     

    You can download HWMONITOR to confirm this if you want.

  • Spoken to Dell Support, and it seems this is a known issue and at this time there is no fix.

    Dell are collecting my PC and refunding. They wouldn't replace with a same spec Studio XPS 8000.

    Little bit saddened that I am having to now order a Studio XPS 8000, and it's costing me an extra £100 for the same spec machine, especially as I order about 20 dells a year and they couldn't at least offer to replace it for the same cost.

    Oh well..... :(

  • I have found that it does not seem to matter what the computer is up to it either does it or it doesn't. The impression I get is the following:

    When the computer starts up something, presumably the BIOS, takes a temperature mesurement and uses this as the normal setting for controlling the CPU. So if you start the computer and the ambient temperature is 15degC, after about a minute the temperature has risen and the control mechanism kicks in to get the temperature back to 15degC. And so the cycle continues.

    So what I have found that seems to work is the following:

    Start the computer and press F2 to get into the BIOS setting.

    Wait for about a minute for things to warm up.

    Press "Save & Exit" to continue.

    The fan speed now remains at a low speed regardless of CPU usage.

    So I get the impression that when you exit the BIOS setup, a new temperature measurement is taken and becomes the new referance point (which of course is now much hotter).

    Am I deluding myself or is this a possible explanation and solution until Dell get their act together.

    Graham

     

     

     

  • Download HWMONITOR from http://www.cpuid.com/hwmonitor.php

    When the fan speeds up, notice that the temp reads 0c for TMPIN1 and the power usage will read 24W.  Then run anything that uses a lot of CPU, you'll see the temperature jump above 0c and the fans will reduce speed.

  • Downloaded the HWMONITOR program and whet I get here is the following:

    TMPIN1 is constantly at about 19degC

    TMPIN0 hovers at about 1 or 2 degC occasionally jumping to somthing higher.

    Everything is fine (FANIN0 is about 1500 rpm)

    Current thinking is this:

    As soon as TMPIN0 goes negative the the temperature control mechanism goes haywire. Can the software hanlde negative numbers or is it treating it as a very larger positive number? The fan would obviously ramp up and try to cool the processor. The temperature gets even colder now at about -2, so you cant get out of the loop until you make the processor do some work and generate some heat.

    Does this make sense?

     

  • I am now convinced that my last post was correct. The temperature control system can't handle the temperature going negativ and treats the reading as a very large positive value.

    So to cut a long story short, my solution, which I shall be monitoring over the next few days, is just to turn the fan upside down. It is easy to do as it just unclips. No need to undo those 4 screws. Using the HWMONITOR program to monitor the value of TMPIN0, originally, under minimum CPU usage, this was hovering around 1-2degC. Reverse the fan and, under the same conditions the temperature hovers around 4-6degC, well away from the 0degC problem point.

    As an additional test, I disconnected the fan completely and monitored the temperature. As it turns out, the combination of the large heatsink and the other fan do a pretty good job of keeping everything cool. However, probably not a good idea for long term usage. Also it does give a message when you reboot about the fan not working.

  • Is there not some way to disable SpeedStep in the BIOS (so the CPU never kicks to low-power mode)?

  • Graham,

    Glad you have confirmed my analysis of the issue, but as Dell have agreed that this is a known issue, they have also agreed to collect and refund my machine.

    But I would be extremely cautious of reversing the fan to reduce the amount of cooling and stopping the temperature reaching 0c.  From my other analysis relating to the correlation of temperature to power usage of the CPU.  When the power usage is at 24w and Temp at 0c, fan runs at 4500rpm, when I start something that causes more CPU usage (eg. SuperPI) the instance the power usage jumps to 115w, then Temp jumps to 20c and fan speed drops to 1800rpm.  I suspect that the temperature sensor hardware is in fact faulty and I would never expect to see a temp of 0c on ANY pc, also the ambient room temperature here is 15c, therefore I suspect the temperature is only being read correctly under CPU load. Running the PC with the fan in reverse may actually cause excessive heat generation and lower the lifespan of the CPU. I highly recommend you DO NOT run your fan in reverse!

    Mayhemm,

    You can disable the speedstep in the bios, which would in theory resolve the issue due to the increase heat being generated from the CPU, but as I run the machine 24x7, this would lead to a very large increase in running cost of the machine at the processor would use the full 115w instead of the lower 11w~24w under low power modes.

    As such this solution is not viable, especially not in a business enviroment where we were discussing purchasing 30 of these machines.

    Thanks, K.

  • Further tests have now shown that reversing the fan does not actually fix the problem as the reduction in the cooling effect is not enough. It changes the temperature by about 1 or 2 degrees so has a marginal improvement. I have found that the ambient temperature of 15degC is the trigger. At this level or cooler, the problem will occur because the monitored temperature goes negative. Higher that 15degC and all appears fine, even at low CPU usage. Next stop Dell.

  • Hi

    i have ordered a new Vostro 430 I7 , yesterday.        :(

     

    i thinking of call DELL for change my order  with VOSTRO 1500

     

    Vostro 1500 have temperature problem ?

     

  • Just had one of those on-line chats with Dell technical suport. They are certainly aware of this issue with the Vostro 430 and say that Dell are currently working on a BIOS update. Presumably this will be V1.0.3 as from a previous post 1.0.2 does not fix the problem.

    Whereabouts on the Dell website are these updates ans I can only find them fro the XPS range?

  • What program do you guys use to measure temperatures and fan speeds?

  • The link was buried in one of the previous posts: http://www.cpuid.com/hwmonitor.php

     

  • I can confirm this problem, the cpu fan noise is unbearable when it goes crazy to 4500 rpm for like 10 min. I tried changing the cpu fan with an artic cooling one but the bios won't accept fan not running at 4500 rpm @ full speed.....

    Found a solution that works so far : using speedfan to control and adjust the cpu fan speed and max it at 2500 rpm. Works well.

    This noise problem is a real design flaw and should be fixed quickly. It is a real deception. You can not use a Vostro 430 in a office it is far too noisy....