Question : Problem: Core2 6300  Processor Overheat (83 Degrees) Celsius Upon Cold Boot

Lately, my desktop keep restarting all of sudden. Until I found out that my Core2 6300 Processor running at too high temperature 83 Degree Celsius. For normal under low load, the process should be around 45 Degree Celsius.

I had tried booting the Desktop from cold state, the temperature straight away shoot up to 86 Degree Celsius.   The processor fan is working fine and I had updated the Chipset drivers as well as flash the bios of the motherboard Intel DQ965F still the problem persist. I need any help fellow EE members could provide. I attached the System Info & Hardware Monitor screenshot for reference.

Answer : Problem: Core2 6300  Processor Overheat (83 Degrees) Celsius Upon Cold Boot

You cooler is most likely not seated correctly.  This means it is likely not pressed evenly and fully up against your processor, therefore even though your cooler appears to be working fine, it isn't in the correct orientation to do its job.

What you need to do is:
-remove your motherboard from your machine
-remove your heatsink/fan assembly from the motherboard
-clean of both the processor and heatsink with isopropyl alcohol and a lintless cloth (I recommend coffee filters)
-put a half-grain of rice sized dab of a thermal compound such as Artic Silver 5 (AS5) on your processor - DO NOT USE A LOT!!!
- replace the heatsink/fan assembly

and you should be alright.