Lenov Yoga C740-14IML laptop freezes

[Rudolfl]

Hi all,

I am really lost on this one. Lenovo Yoga C740-14IML. Running W11. Machine freezes intermittently. It may work for hours, then suddenly freeze. Or it may freeze as soon as it starts and gets to lock screen.
Now, what was checked:
1. BIOS and all drivers are up to date. W11 was re-installed. No additional software is running. Naturally, no viruses, as it is a fresh install
2. RAM test passed with memtest86
3. SSD is tested and reports healthy status. It is a Samsung M2 SSD MZVLB5512HBJQ. Unfortunately, Samsung "magician" software is not supporting this drive fully and can not run all tests, but all reports are 100% healthy. chkdsk returns no errors
4. Temperature is not high. Fans working. All temperatures (core, graphics, SSD) at about 50-55 degree. I run hotCPU to stress test the CPU and RAM. Temperature jumps to about 72 degrees, but machine is stable. Then fans kick in and temperature drops. In fact, I was not able to freeze it running stress test.

At the moment, really lost as to what may cause it. Perhaps, some compatibility with W11?

Any advice is greatly appreciated.

Thanks
Rudolf

[Rudolfl]

An update.
Replaced SSD with one I had handy. Same problem.
Lifted the CPU heatsink, found thermal paste being dry. Cleaned it off and replaced with fresh, high performance one. Problem is still there.
Also tried to but Linux off USB. Same -- freezes after some time.

Really lost here

[tomodachi]

Ever tried to run memory test ?

[Rudolfl]

Ever tried to run memory test ?

Yes, as per my original post -- memtest86 passed all tests

[mcplslg123]

Newer lenovo laptops specially 10th gen onwards has this problem. There is no unique solution. However,on multiple occassions i had success by desoldering mosfets on VCORE/GPU area,putting fresh solder on the pcb pads and some flux and re soldering the same mosfets back. Worked on many occassions but definitely not every time. So you can try. It was not heat at play while soldering/de soldering as they worked for more then 6 months after repairs. The solder quality on these lenovo boards is a big issue.

However, be careful with the amount of heat applied as these boards dont tolerate heat well and surrounding components may just fly away. So better to cover the surroundings with kapeton tape before proceeding.

[Rudolfl]

Thank you for the tip. I can't find my heat tape, so ordered new one today. Will try then. I may post photo of the PCB before, though, just to make sure I am working on right parts.

Rudolf