I think I solved my ‘laptop instantaneous shutdown’ problem. But it makes no sense. Please help.

cs_toms

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Dec 6, 2013
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I am having a problem for 5 weeks that I can't solve and it's driving me crazy. By the end of the post, you’ll see why I need help from you guys.

[EDIT: My warranty expires shortly. There are so many unexplained things, asked as 3 Qs at the end, that I have to assume this problem may recur after warranty period. Having more info will help me decide if I can use my warranty to prevent this prob. from recurring. I have added this edit for alyoshka's response.]

This began 5 weeks back. During normal operation, my laptop shutdown suddenly. It was an instantaneous shutdown like the power to the motherboard was cut-off suddenly.

This happened 2 or 3 more times. After searching the net, I found this explanation to fit best: 'The GPU thermal paste had dried up. So during usage when there was a sudden increase in temperature, the sensor tripped and caused the shutdown.' This made sense because:
1. It only happened when 'Power Options -> Graphics Power settings' was set to 'Maximize performance’ instead of Maximise battery life.
2. I couldn't feel any heat on the surface of the laptop. If it was just the GPU that was heating up (but no other component) then I wouldn't be able to feel it outside on laptop surface (right?)

To monitor the temperatures I installed HWinfo and GPU-Z and Speedfan.

Then I called Dell and had them replace the entire setup (Fan,sink,thermal paste etc.) It NEVER shutdown again during normal usage.

But just to be sure, I did the following test: I ran three 720p videos simultaneously in 3 players. The laptop shutdown in 20 mins. I kept repeating it.
Again and again, the laptop would work fine under normal operation and under heavy CPU usage like heavy video editing. But it would always fail when running three 720p videos.

This went on for quite a while. I
1. updated BIOS.
2. Ran Dell’s extended and H/W diagnostics tests.
3.Since it always occurred when plugged in to adapter, I thought it was a power supply problem. I installed BatteryMon and checked voltage supply - It was 11.5 V in battery and 12.5 V when plugged in. This is well within range.
Also, frustratingly, it shutdown twice when running on battery after this. So, I ruled out voltage problem.


Then I read on some forums that, SpeedFan can cause shutdown problems because it sets GPU Fan speed at a constant 30% at all times. I checked and that's what it looked like.
I uninstalled it today, and suddenly three 720p files, a NFS game under high settings have been running for the last 5 hours without any shutdown problem.

THIS SEEMS TO BE THE ONLY EXPLANATION:
At first, my GPU thermal paste dried up. So, GPU heated up sometimes under light use and caused shutdown.
Then Dell replaced thermal paste and solved this problem and it started working fine in light to medium use.

But by then I had installed Speedfan and HWinfo. So my GPU Fan speed was set to 30%. This caused the GPU to heat up UNDER heavy use like three 720p files. So it worked fine under normal use but kept shutting down under three 720 p files.
Now that I have uninstalled it, both problems are solved and it's working fine under heavy use for 5 hrs.

MY Q IS:

1.All of this diagnosis seems like a huge coincidence. Thousands of ppl use speedfan. But this rare problem happened to me? AND it happened when there was a totally unrelated problem already happening to me?

2.During 3X720p playback, the temp never went over 70*C. It fell back down to 60*C in a few mins. Also, the Fan RPM was not constant [It would run anywhere between 2 rpm to 1100 rpm. Shouldn't it run at the same speed if speedfan set it to a constant 30% ? Also, isn't 1100 rpm really low during heavy use - what does THAT mean??!]

3.Also, what does it mean that it only rarely happens in battery but always when plugged in [Every setting and usage are the exact same in both]?

You see why I need your help?! ;-)
I ask this very respectfully: Please do not give me advice or information that are just guesses. I am already quite confused enough! Again, I ask this respectfully.
 

alyoshka

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Oct 2, 2009
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Well, to put all your queries to rest in one answer....
You're like one in ten thousand people who face this problem.... the rest of the Q&A are all related to that one in a thousand case... thus logically, no conclusive explanation lies for the problem you already solved and have already reached the final answers to , yourself.
 

cs_toms

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Dec 6, 2013
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My warranty expires shortly. Having more information will help me decide if I could use my warranty to prevent this from recurring. While you what you say might be true, seeing how unlikely it is,I would like a few people's thoughts on this. Thank you for the response though.
 
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