Hi BachNg,
I appreciate the time and effort that you took to troubleshoot the issue. It seems heatsink and fan needs to be replaced.
If the system is under warranty then please contact me through a private message by clicking on my name highlighted in blue. On the next page, click the envelope icon and provide your service tag and contact information so I may access your system records.
And, if the system is out of warranty then you contact our Expired Warranty Support at the link below:
If you have any further queries please feel free to contact us.
Thanks and Regards
Sandeep P
#iworkfordell