Apr 11, 2021
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Hi everyone,
i have a 15-cb028nl HP about 3 years old. A couple of weeks ago i decided to clean up the fans because they were kind of noisy (but the laptop was working fine). So i removed them (it is a couple of identical fans) cleaned them with a cloth and put them back into place. After that, my laptop was not booting up anymore (i got a 90D error about system temperature). So i removed the heatskink as well (it is one single piece for both CPU and GPU), cleaned cpu and gpu using arctic silver products, reapplied the thermal compound. I did this operation 3-4 times, but i still had the same issue. I also updated the BIOS version.

Yesterday i finally managed to boot my laptop up (i did not boot directly, but i logged into the UEFI system diagnostics first, ran some tests, which passed, and then went on with the boot up). After that the laptop booted up fine, and when it boots up like that it looks kind of stable (i got some data from SpeedFan application):
  • ACPI between 45 and 60 celsius
  • the 4 cpus are between 25/40 celsius
  • fan 1 --> 2000 rpm ca, fan 2 --> 200 rpm ca (what is a normal value here?)
if i try to boot it up normally, however, i hear the fans spinning really fast and the laptop shuts down, ending up in the same issue.
So it seems that once i get past the boot up, where the fans spin faster, the system can work properly.

So my question is, what could be wrong here?
Initially, since i touched the fans only, i thought those could be the problem. But then i saw them spinning so i assumed that that was not the main issue. That s why i went for the thermal paste. Maybe it was just a coincidence that the issue happened after i touched the fans, and the problem would have showed up eventually, also because i ve been using the laptop on a blanket latelly (which is wrong, i know...).

Now I feel the heatsink a bit warm though, but the data from fanspeed are kind of reassuring (i also have hp coolsense enabled).
What do you suggest doing in this case, how can i understand where the issue is?
  1. replace the fans (maybe they are not pushing enough air)?
  2. replace the heatsink (maybe it does not work properly anymore)?
  3. replace both of them?
  4. could be a sensor/cmos problem?
appreciate any input here,
thanks
 
Apr 11, 2021
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Hi all, small update.
i have replaced both the heatsink and the fans and i m facing the exact same issue. I still can turn my laptop on using the workaround, but the performances (gaming for example) are much worse. I ve also noticed that the issue appears when the laptop tries to recover from the hibernation mode as well; I don't know what to do, i am a bit out of options. I would prefer not buying a new laptop, when it seems that this one can still work fine. Is there a way to check if it is a sensor/motherboard problem?
 

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