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Dell Latitude D620 CPU fan

Last response: in Laptops & Notebooks
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February 23, 2013 11:27:03 PM

So I performed an upgrade on my Dell D620. The CPU fan was working fine before I took it apart. I swapped the processor from a Core Duo T2400 up to a Core 2 Duo T7200. It is recognised fine in the bios, and it boots to windows with no issues. However, the CPU fan is not working at all, and the fan control in certain applications (for example Argus Monitor) no longer recognises any fans. I ensured that the fan is still firmly plugged in and that there is no damage to the wires.

What could be the issue here?
a b à CPUs
February 23, 2013 11:50:24 PM

Try resetting the CMOS/BIOS to see if that fixes anything
February 24, 2013 2:54:27 PM

stickmansam said:
Try resetting the CMOS/BIOS to see if that fixes anything


Tried that with no luck.
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February 24, 2013 3:04:27 PM

Bit of news. The fan controllers now work, and I can control the speed manually. With the fans at about 2500 RPM, the CPU idles at about 45 degrees. Is this any good ?

So basically, I can turn on the fan and manually control the speed. But if I turn off manual control and set it to auto, the fan drops to 0, completely off, and refuses to do anything. What can I do to get it working with automatic control again ? Or what speed should I set it at worst case ?
a c 101 à CPUs
a b D Laptop
February 24, 2013 3:19:52 PM

Try putting the old chip back in and see if it the fan kicks in. If it does, then it's the chip. the T7200 has a higher thermal load and may be drawing more power or may use a slightly different internal thermal probe that the BIOS can't properly recognize, so it thinks it's too cool for school and doesn't need the fan on. That would be my guess though, since you went from a Core Duo to a Core 2 Duo, even though it's the same package, the BIOS lacks the knowledge to read the temperature properly and therefore won't kick the fans on. Swapping the CPU back would prove/disprove this.
February 24, 2013 4:05:14 PM

getochkn said:
Try putting the old chip back in and see if it the fan kicks in. If it does, then it's the chip. the T7200 has a higher thermal load and may be drawing more power or may use a slightly different internal thermal probe that the BIOS can't properly recognize, so it thinks it's too cool for school and doesn't need the fan on. That would be my guess though, since you went from a Core Duo to a Core 2 Duo, even though it's the same package, the BIOS lacks the knowledge to read the temperature properly and therefore won't kick the fans on. Swapping the CPU back would prove/disprove this.


You reminded me of something, I have not yet updated the BIOS. Turns out I'm running revision A05 when the latest is 2 years newer, A10. I will have a go of updating that first before I try your suggestion if necessary. Do the temps seem OK to you? Seems to run at about 65 degrees under load. Much better than before.
February 24, 2013 5:24:32 PM

I think you may be right here. The CPU fan does kick in by itself, but only when the temperature hits about 75 degrees. Once it is back down to 60 ish, it stops. It seems to think that its cooler than it actually is. Is there any way to change the settings of the sensor in order to lower the threshold? One time it did actually work as intended, but only for a short while and not immediately after boot either. I have known someone to do this exact same upgrade with no issues, so I am fairly confident it should work ok.
a b à CPUs
February 24, 2013 5:49:44 PM

try checking the bios settings for the cpu fan, it might be set to only activate after it hits a certain temp and updatibg bios can't hurt
February 24, 2013 8:29:22 PM

stickmansam said:
try checking the bios settings for the cpu fan, it might be set to only activate after it hits a certain temp and updatibg bios can't hurt


Forgot to mention that I did eventually update the bios to the latest (A10) with no difference. Nothing in there in terms of settings. I ended up using i8kFanGUI with normal settings. Allows the fan to stay at 2500 rpm above 40 degrees. There's not much fine control so its a bit noisier than it used to be, but the temperatures are about 45 idle and 65 load, so I think that's reasonable enough. I realise maybe I should have used better thermal compound, but it will do.

Seems as though I will have to just set it to launch on startup and have that control the system for me. Not the most ideal thing ever but it seems to work! Thanks for the assistance.
a c 101 à CPUs
a b D Laptop
February 24, 2013 8:31:25 PM

If it works and keeps it cool, and you're happy with that, go with it. I had an old laptop with a dead fan header. Had to wire it internally and was loud and on all the time, but worked for another few years. Beats tossing it.
!