1) FOLLOW Anti-Static Precautions.
Your body carries Static electricity. Static WILL fry out (Short Circuit), the delicate hardware components of a computer.
Relieve your body of Static BEFORE working on your computer.
Computer on a table, computer Unplugged from power, computer case open;
TOUCH an unpainted surface of the metal frame of the open computer case.
This action will relieve your body of Static.
IF you leave your computer in the middle of working on it, be SURE to Touch the metal frame again upon your return.
A Processor is the MOST susceptible hardware component to Static Shock.
2) Clean the top of the Processor, and bottom of the Heatsink THOROUGHLY.
Start with a plastic scraping device, (Old credit card?), and scrape off as much of the old Thermal Paste as you can.
If there is a Thermal Pad, carefully peel it off, throw it away. CANNOT be reused.
Scrape with the plastic scraper.
Follow with Q-tips dipped in Isopropyl Alcohol. (Rubbing alcohol)
91 percent is best, but 70 will do.
May take a LOT of alcohol dipped Q-tips as it's usually a gooey mess.
MUST be clean enough when you are done, that you could literally eat off of it.
Isopropyl Alcohol is EXTREMELY FLAMMABLE!
Use in a WELL ventilated area with NO sparks or flames present.
Thermal paste has to be PROPERLY applied.
NOTE about thermal paste that contains real silver.
(One example Artic Silver 5 )
Silver is an excellent conductor of heat. Will transfer the heat from the Processor to Heatsink very well.
Silver is also an excellent conductor of Electricity.
IF you apply too much it will ooze off of the Processor, once the Processor reaches operating temperature.
Will ooze onto the pins of the processor, or pins of the processor socket.
Will ooze down on solder joints.
Result is Short Circuit.
(If this has transpired, follow Anti-Static Precautions, remove Heatsink, and Processor, use alcohol dipped Q-tips to remove all thermal paste, start over. Sometimes you can get to it in time, and nothing is permanently damaged )
It is really best to install the Processor with the motherboard removed.
Reasoning is that you can hold the motherboard flat, up to your eyes, and look across it.
See if the Heatsink is sitting perfectly flat, or there is a crack of daylight showing in-between the Processor, and Heatsink
Heatsink on Processor MUST be sitting flat.
3) Watch power cable to Processor fan. I have had a few where one of the pin connections in the power cable's connector, pushed out a little.
Doing so meant the wire to that pin, was NOT plugged all the way in.
The pin in the power cable, did not plug all the way into the 'connector tube', of the Processor fan cable's connector.
('Connector tube' = Molex metal female terminal,http://www.molex.com/molex/products/datasheet.jsp?part=active/0002081202_CRIMP_TERMINALS.xml&channel=Products&Lang=en-US
This means the Processor fan will run intermittently, or not at all.
Result is overheating of the Processor.
4) Make sure the Processor fan wires are plugged into the motherboard.
Computer case open, computer turned on, watch the Processor fan. Make sure it is spinning, and seems to be spinning at the correct RPM's. (Revolutions Per Minute)
For additional questions please post in a Comment.