Question Laptop keep shutting down unexpectedly after cleaning and repasting!

Sep 29, 2020
My Asus S45lb is a 4-5 year-old Laptop.
intel i3-4010U
Nvidia GT 740M
6 GB Ram (4gb ddr3 i sdram + 2gb ddr3 sdram SKHynix)
500GB HGST HT545050A7E680
i notice that my laptop is running too hot when both cpu and dedicated gpu on a high load and the gpu thermal throttled. Granted it might be the cost of not cleaning and dust built up over those 4 years of usage.
So decided to clean my laptop. Before i clean it, i took some thermal and performance test. Using R20 , CPU-Z for cpu, Heaven Imagine for gpu and hwi64 for recording temp.

Previously i have upgraded my ram(integrated) from 4gb to 6gb by adding 2gb to the expansion ram slot and adding new hdd using caddy hdd to replace my dvd drive.
before doing the cleaning procedure I’m well aware how to do it and make sure i understand what I’m doing by researching on the internet. So i’ve come prepared (so i’ve thought).

After opening up the back cover, taking of the necessary screw that hold the cooling assembly and fan and also keep in mind what screw goes where, i’ve come to the part when u need to take of cooling block from gpu and cpu dye. I pull slightly and it wont came of, So i take my time to pull carefully with abit of force and finally it came of! but in my mind, i was a bit worried to take that amount of force to sensitive hardware that could possibly damage the hardware.

The thermal paste was dry and the consistency hard like plastic. But after i carefully took bit of time using 99% alcohol (ipa) and cotton buds all of the old thermal paste slowly dissolving away. When i clean the cpu it was easy but when i do the gpu dye it was a different story. the old thermal paste is much harder also not only covering the dye but also couple of the small tiny surface mounted component on gpu. then I proceed to clean the fan and cpu/gpu block.
and wiping away any dust from behind the mobo.

After cleaning was done i used arctic mx-4 thermal compound to repasted my cpu and gpu with an adequate amount ( long line and a dot) and doing the crisscross pattern to screw that cooling assembly back on its place. Make sure everything was back in place then i closed the back cover.

On the initial boot everything was a ok. Then i do the same test. First was 15 min idle temp and it passed that. Cpu-z 15 min it passed that. I took the laptop a chance to cool down to its idle temp before proceeding to gpu test but when heaven benchmark just started it suddenly shutdown. Then i cold boot the laptop and do the heaven benchmark. It does the same thing sudden shutdown.

i opened back up my laptop and repasted the gpu and cpu. Then everything went okey again temp was good not even thermal throttling again! after it finish the test i even be able to overclock the gpu and didnt hit 80°c but for lifespan sake and thermal headroom i change that again to its normal clock.

But the next day i have the same problem again when cpu on full load and gpu was utilized it suddenly shutdown again! I were on memu android emulator which take half of cpu and gpu performace. Then i open up my laptop again and put it sideways and took a giant fan and to blow into the laptop. Everything is ok even when i did the heaven and cpuz combo temp was fenomenal at only 67°c both cpu and gpu.
But once i turn of the fan after 5 sec. It shutdown again!

I took the precusion to disable my gpu using device manager and relay on igpu but after a couple hours of usage it sudden shutdown again! And noted that cpu and gpu temp was nominal. Never exceeded the t junction temp on hwi64. But it kept shutdown with no warning!

My thoughts ? the problem its obviously caused by overheating then thermal shutdown but I don’t know that the components causes that :/

I need your help! what is the problem ? How can i fix it ?
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