Shared Knowledge
"HP Pavilion zd7000 - How to Solve Overheating Related Shutdowns"
22 December 2010
Summary: random laptop shutdowns are usually caused by the CPU chip becoming so hot, it shuts the entire system down to protect itself from heat damage. The causes of poor CPU chip cooling include: laptop fan vents blocked; fan clogged with debris; fan not turning or poor thermal transfer between CPU chip and cooling fan.
Background:
The central processing unit (CPU) chip of all personal computers (PCs) have millions of elements in them that give off heat.
All CPU chips have a built-in thermometer.
As CPU temperature approaches a critical valve, above which CPU circuit damage could occur, the CPU protects itself by shutting down the entire system.
The temperature of a CPU chip is a function of the computing load it is handling. The more "work" the CPU is doing over an extended period of time, the hotter it will become.
Poor CPU cooling can be due to: laptop case cooling vents covered; cooling fan clogged or choked with debris; cooling fan not turning or poor thermal transfer between top of CPU and cooling fan assembly.
Tools and supplies needed:
2 cans of compressed air if new cooling fan not required. Available at Staples and many other places.
Phillips screwdriver.
Needle nose pliers.
New cooling fan if installed fan not turning. Must be for zd7000. Available on eBay, perhaps from HP and other Internet suppliers.
Thermal conductive paste. Available at Radio Shack or via the Internet.
Fixing random system shutdowns:
With system powered on, turn it over to observe cooling fans. Are they turning at all? If not, you must replace cooling fan assembly.
Shut down Windows.
Remove power adapter plug from laptop.
Remove battery.
Remove the 8 screws holding the fan assembly cover in place.
Lift up and remove the fan assembly cover.
With the cooling fan assembly exposed, gently disconnect the 2 fan connectors at each end of the assembly. This may require the use of needle nose pliers. Do not simple tug on wires to get connectors to disengage.
Loosen the 4 Philips head screws holding the cooling fan assembly in place. If you look closely, you will see the numbers 1, 2, 3 and 4 stamped into the metal of the fan assembly. Loosen the screws in number order from 1 to 4.
With the 4 screws loosened, gently pull the fan assembly away from the side of the laptop case and move it towards the rear of the case. Continue to gently move the fan assembly towards the rear until air intake is clear of the front of the laptop case. Now lift the fan assembly out of the laptop. If when you go to remove the fan assembly it does not want to move or only moves partially, check that all screws are completely unthreaded from the motherboard standoffs.
Although not show in the image above, when you remove the fan assembly, you should find the large chip (CPU) covered in some white caulk-type substance. You should also find the large copper area on the fan assembly to have this same white substance. The white is the old thermal conductive paste.
Using a Kleenex, gently remove old thermal paste from the fan assembly. It should come off easily.
Use a Kleenex to remove the old thermal paste from the top of the CPU chip.
Now apply new thermal paste to the top of the CPU chip. Place a small blob of paste in the center of the chip and then use a finger to spread it evenly over the chip. Note that the smaller fan does not make contact with the 2 motherboard elements shown in the large rectangular black area and thus do not require thermal paste. Note: thermal paste is sticky and you need to remove from finger immediately after you are done spreading paste on top of the CPU chip.
With new thermal paste in place on the top of the CPU chip, move the fan assembly (old or new) back into the zd7000 case. Again you will have to place the small fan end of the assembly into the case first and then gently move it towards the front and side of the case.
Alignment of the 4 screws holding the fan assembly to the motherboard is a little tricky. Take the small Philips screwdriver and attempt to get screw number 1 to tighten down. If it does not thread, gently move the fan assembly a little one way or another and try to get the screw to thread again. Once screw 1 begins to thread, stop and move to screw 2. Do not tighten down any of the 4 screws until all have been threaded into their motherboard standoffs. Again, if you have trouble getting screw number 2 to start threading, gently move the fan assembly a little towards the front or back of the case and towards or away from the side of the case. Go slow, you will find the exact spot required.
Once all fan assembly screws have been threaded into their motherboard standoffs, tighten down screw 1, then screw 2, 3 and then 4.
Now reconnect the 2 fan connectors. These connectors are right up against the fan assembly and might require you to use small needle hose pliers to reconnect them. These connectors will only go on the motherboard socket one way. If you look at the fan connector you will notice that the holes (electrical female) are closer to one edge than the other. If you examine the motherboard fan sockets you will notice that they have male electrical pins closer to one side of the socket than the other. The fan connector holes need to align with the motherboard socket pins. Go slow.
If the cooling fan was not replaced, use a can of compressed air to blow all debris off the fan blades and inside the circular housing of the fans. Then blow air in through the intake vents and then air out the air out vents. Continue to blow air through the fan assembly until no more dust, debris will come out. If you are sensitive to dust, take appropriate measures to shield your nose and eyes.
With the fan assembly back in place with both fan's electrically connected to the motherboard and the fan blades and housing as clean as you can get them, replace the fan assembly cover.
Reinstall battery, reconnect the power adapter and turn on the dz7000. Almost immediately you should notice how quiet the fans are.
If all appears well, you might try to test CPU cooling by heavily loading the processor by running an antivirus application or other. What you want is for the CPU to be used 100% for several hours. My test was to run an AVG antivirus scan, a Spybot Search and Destroy scan and Slingbox player all at the same time. With the CPU being used 100%, the system did not shut down once in a 5 hour period and the fans never even sped up all that much from normal CPU idle (low heat) condition.