NOTE- THIS METHOD WORKS ON ROOTED DEVICES ONLY.
Step 1- Download Wake Lock Here.
Step 2- Install and open it. Do not forget to provide superuser permissions.
Step 3- Enable the option PARTIAL_WAKE_LOCK.
Step 4- Go to Options and enable AUTO START ON BOOT.
This option automatically apply the PARTIAL_WAKE_LOCK settings when phone is rebooted by the user.
This method fixed random reboot problem in my Mi3 which is on CyanogenMod 11 ROM.
Hope this method works for you guys too. Any problem related to above method?? Just drop it in the comment sections below we will provide support ASAP.
Stay tuned to TECHULK.