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Model: Samsung R590
CPU: Intel i5-450M 2.4Ghz -> 2.66Ghz
OS: Windows 7 Home Premium 64 with SP1 (after restoring tested also without any updates)

It has 4 years now. After 2,5 - 3 years it started to turn off when I was playing games. It was then cleaned from dust and thermal grease was changed. This helped only a bit. The problem returned after a few weeks. Then i managed to change the maximum processor state to 90% in the power options and it prevented turning off for a few months, but caused an fps loss. Then it started to turn off again even with this setting. I had to clean it from dust (there wasn't too much of it) several times in this period of time to get it back to work. In the last week the problem occured again. I had enough and decided to do everything I could, which included:

  1. Restoring system to factory settings with Samsung Recovery Solution software included with the laptop which kept the factory system image with default drivers and Samsung programs.
  2. Cleaning from dust and changing thermal grease by myself.
  3. Checking the heatpipe with lighter if it transfers the heat to the other side (when disassembled of course).

It didn't help. If the setting in power options is not lower than 100%, laptop turns off after a minute of testing the processor with OCCT (if I disable temperature cap in this program. With the cap of 85*C the test stops in less than 10 seconds).

In the passive state the temperature of the processor is 35-40*C. With 99% maximum processor state setting, when testing with OCCT, temperature is not higher than 86*C and as I read on the internet it's probably the normal temperature for laptop's processors. When maximum processor state is set to 100% (default setting) during the test, turbo boost overclocks the processor to 2.66Ghz, temperature gradually increases up to 105*C (which seems to be a safety cap) in around 1 minute and then the laptop turns off.

GPU temperatures during tests of GPU are fine, so it's only CPU problem.

Question: What may be the reason of that and can I do anything to fix this? System is restored to factory settings along with standard drivers, it's clean inside with fresh thermal grease, heatpipe transports heat, fan is working, BIOS is original so the conditions are similar to initial, so why it overheats?

Additional research: (added 4.12.2014)

I did a little research with Speedfan, temps and fan speed (by ear). When 99% and testing, fan speed is fast and uniform. But when 100% the speed is fast first, then it eases down a bit and then accelerates again and so on. I think if it could keep the speed it wouldn't overheat. link this is a record of temps when testing with 100% (I stopped it after ~35 secs to prevent the turn off). There is something weird. At some point temperatures from "core" switch with that from "temp". The fan eases down in the same moment. It probably thinks that the temperature is lower so it don't have to work on full speed but it's wrong. Temp1 and Temp2 are sensors from ACPI chip. That behaviour doesn't exist when CPU is on 99%.

  • What thermal paste did you use? Artic Silver? Did you monitor the fan for an hour? Fan problems can be intermittent. I assume you completely removed all of the old thermal paste before applying new. Are the mounting brackets that hold the heat sink in place as tight as they were orginally? (Any looseness could reduce the efficiency of thermal transfer.) – cybernard Nov 28 '14 at 16:41
  • @cybernard, I used AG Gold. I don't know what was the previous one because it wasn't me who changed it, but the problem exists independently. And of course I removed the old one and cleared the surface well with a cotton bud with a little of alcohol carefully. I tried to monitor fan speed with HWiNFO64, it showed me a lot of sensor data like temperatures and voltages but there was no fan speed (and I saw it on a movie when someone was using it so probably it's inaccesible in this model, bios version, idk). I also wanted to change the fan speed but it's also impossible. – kfinto Nov 28 '14 at 23:27
  • @cybernard, there are no brackets, only 4 screws which I screwed as strong as i could. I didn't push it to check if it's not moving, though. – kfinto Nov 28 '14 at 23:27
  • Try Speedfan for monitoring the fan speed. How hot does the heatpipe get? If it gets extremely hot then the heatsink has a problem. Feel the fins on the heatsink are they extremely hot? Heat moves from CPU to heatsink to heatpipe to heatsink and the fan blows the heat into the air. Your problem is in one of those steps. – cybernard Nov 29 '14 at 2:46
  • link it's everything that Speedfan shows to me, so as I wrote, I'm unable to get the speed. What may be the reason? link This is an example image of the cooling system I have. There is just a "plate" on the CPU and then just a pipe, there is no additional heatsink at the end near the fan. The end of the pipe hides inside the fan cover so I am unable to touch it when assembled. – kfinto Dec 1 '14 at 13:24
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I had the same problem with the same model (R509). Eventually, I brought it to a repair shop of a guy who used to work for Dell. The guy found that the heat dispersion/transfer was poor, due to poor material contact. He re-installed the processor, using a different/more/new thermal paste. And he may have done something else as well, I'm not 100% sure of that. Although he could/did not increase the fan speed. But it did cure my problem. The overheating disappeared -- since then, it has not gone higher than some 80 deg C.

And I would suggest to have it fixed by a pro, because overheating can damage the processor.

EDIT: I misread your OP. I thought you said that you had cleaned thermal grease, but I now see that you had changed it, and that you meant the thermal paste with it. Sorry for that. And come to think of it, it might just be that the guy who had fixed the problem for me changed the Maximum Processor State setting back to default, which is 50% in my case... I can't remember having it changed myself, but that might still be possible.

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