Monday, February 17, 2014

Replacing the CPU Fan on an HP Pavilion G7 Laptop

There is no shortage of stuff to fix at my house. I can almost always take my pick of plumbing, appliance and even computer problems. At work there's usually a long list of people waiting for me to fix something, and at home it's no different. The missus was having fan/heat problems with her HP Pavilion G7 laptop, which was is than a year old. She's been a trooper waiting for me to fix it, and the day finally came when we had the parts and I had the time.

At first, the fan was just a little loud. But then the fan started getting louder, before failing completely and overheating the computer every time she went to use it. One part of the job she could make go faster was Googling the model number and ordering the replacement fan.

The Supplies

Replacement FanI had the missus find and order it. I think she paid about $25 for it. 
Thermal GreaseRe-apply to the CPU before putting the heatsink back on with the new fan. My replacement fan came with thermal grease. If not, just order some Arctic Silver
Can of AirUsed to clean the inside of the case and the vents.
Rubbing AlcoholUsed to remove the existing thermal grease from the heatsink and CPU.
Q-TipsCotton balls would probably work just fine as well.

The Tools

The tools for this job are very basic. If you find yourself needing a lot of tools, then you are probably doing something wrong.

Philips #0 ScrewdriverUsed to remove and replace all of the small mounting screws
Needle Nose PliersUsed to very gently work with some of the ribbon cables
Flat Blade Pocket KnifeUsed to gently remove the case cover and keyboard. Any knife will do, but it has to be very flat and smallish. I used my Victorinox Executive. Most Swiss army knives have the perfect blade shape for this job, and I even saw a video where someone used a putty knife.


Close the lid and flip the laptop over, bottom side up.

Take the battery out.

Take off the back panel. There is one screw which doesn't come off, and then the entire panel slides toward the front of the laptop. There's even an arrow on mine, showing you which direction to slid it.

Take all the screws off the back. If you see a screw, take it off.

Once you unscrew the single mounting screw from the wi-fi board, disconnect it from the motherboard. The screw on mine didn't come off, so I left it attached to the little board. FYI for this job, I left the RAM mounted through the entire process.

Disconnect the DVD drive connector. I missed this step and had to disconnect it to free the motherboard.

Slide the DVD drive out.

Below I lined the DVD drive up with the single screw which holds it in.

Flip the laptop back over and open the lid.

Take a small pocket knife or something flat and gently pry the keyboard off. Don't put too much force on it. You should be able to gently work it off with a small knife.

Disconnect and remove the keyboard. There's a little lever that you lift up, otherwise you could gently pull it straight out like I did.

In the photo below, I removed the keyboard and flipped it over so you can see how the ribbon cable connects to the motherboard through the window.

Take the 4 mounting screws off the keyboard plate.

Disconnect the three connectors, being very careful not to damage them. One is a push-in connector and the other two are ribbon cables. In the photo below you can clearly see the three connectors.

Using a flat blade or tool, gently pry off the plastic cover. There are a bunch of plastic hooks--I call them 'snappers' --which hold the cover on. Work your way around the case with a knife, gently making then disengage. When I got to the empty space where the DVD drive was, it got a little dicey and I was worried that I would break part of the case, so be careful.

In the photo below I have removed the cover and flipped it over so you can see the underside.

Disconnect the DVD drive connector. You can see it floating there in the photo.

Take out the motherboard mounting screw in the lower left hand corner--mine only had one screw.

Disconnect the ribbon cable on the upper right hand side. It's for a USB port if memory serves me. Now disconnect the power connector right below it.

Disconnect the display connector on the upper left hand corner. There's a little plastic handle which you can grab and pull straight up.

The motherboard should now be free now--take it out of the case. At this point I went into the living room and handed the laptop to the missus looking like the picture below. I said "Ok, I'm done working on your laptop. It's even a little lighter now."

Below you can see the wi-fi board sitting there as well as a few connectors. About the only major components still attached are the display and the hard drive, which you can see is sitting under its own cubby on the other side.

Unlike most desktops I've worked on, the motherboard is mounted upside down.

Now flip the motherboard over to access the fan/heatsink.

Disconnect the fan and take off the little clip as shown.I have no idea what this clip is for, other than I thought I broke it off and then realized I had slid it off. It doesn't seem to have any purpose I can see, but just for giggles I'll be putting it back the way it was.

Unscrew the 4 CPU heatsink screws, and the entire assembly should come free with the fan. The fan assembly is just kind of stuck to the board with some light adhesive, so you will need to gently work it free.

Take off the two tiny screws holding the fan to the heatsink assembly. These are the only two screws which are different in this project. In the picture above, you can see that I kept them all in the same pile to illustrate that point.

Take a Q-tip with some rubbing alcohol, and thoroughly clean the old thermal grease from both the heatsink and CPU

The heatsink will probably be a clumpy mess with old thermal grease. Cleaning mine made some go into the little nooks next to it, which is fine. The goal is to have the part of the heatsink that touches the CPU look like nice, shiny copper.

It should go without saying that you want to be very gentle with the CPU. Don't drip excess alcohol or get any debris in it. When it's clean, it should have a mirror finish like the photo below. Also notice that this machine has an AMD A8-4500M processor, which is a really nice chip. It's a "quad core" with a video GPU built in, so it has graphics performance which rivals much more expensive machines.

Mount the new fan on the heatsink assembly using the two tiny screws which you hopefully didn't lose. One of them stuck to my hand and flung itself on the hard wood floor, and luckily I heard it bounce and recovered it. Your rebuilt and shiny copper heatsink assembly should now be ready to remount to the motherboard and CPU.

Put a small dab of new thermal grease on the CPU. I know some technicians recommend being very liberal with it, but this is where I disagree. If you put too much, then it will be messy, and too much can even have the opposite intended effect and weaken the properties of the grease. You want a very thin film over most/all of the CPU when the heatsink is mounted, so try to "guesstimate" how far it will spread out when that dab you put is sitting between the heatsink and CPU. I little too much is OK, and being a little light on it is even OK. The goal is to have a thin film of it cover as much of the CPU surface area as possible without making a mess of it.

The fan I purchased came with a little syringe of thermal grease, which I used. I also bought some Arctic silver, which is the best you can get. In this case I'm using the grease that came with it and saving the Arctic Silver for a higher end machine that runs hotter. When I put some on, it came out a little faster than I anticipated, so I ended up with slightly more than I wanted, which is fine.

Now, remount the heatsink assembly very carefully. You want to press the copper plate onto the CPU in such a way to spread the grease out evenly and not make a mess. Tighten the 4 screws and reconnect the fan connector. You want the screws to be nice and snug without being over-tightened.

Don't forget to put the little plastic retaining clip back on if you took it off. I'm not sure I see the purpose of it, and I almost forgot to put it back on.

Below you can see the new fan mounted on the heatsink, which has been mounted on the CPU and it's ready to go.

Hopefully everything went well and you haven't damaged anything. You are now ready to begin the reassembly process. At this point I would just double check everything, especially the fan connector. If you forget to plug the fan in, you'll be repeating virtually the whole disassembly process. So spend that extra minute here with the motherboard in front of you.


Before mounting the motherboard, it's probably a good idea to blow the whole area clean with a can o'air like I did. Now carefully flip the motherboard over and put it back in its cubby, putting the single mounting screw back on.

Make sure all the side ports and connectors line up with the case. The USB, ethernet, HDMI and VGA connectors should be aligned and look normal.

Reconnect the display and DVD drive connectors. Line them up perfectly and just press them straight down.

Reconnect the power cable on the upper right hand side of the motherboard, and then reconnect the USB ribbon cable which goes right above it. If you were hasty like me and just yanked it the ribbon cable out, gently lift the little lever up, push the cable straight in, and lower the lever.

Now you will want to remount the plastic top cover. Make sure the three connectors are sticking up in their respective windows or it will be a hassle to unsnap the cover once all the snappers engage.

When I first disconnected the touchpad cable, the little white plastic lever had fallen off. The two ribbon cables gave me the most grief for the whole job because they are so delicate, and the little levers are so prone to coming off. I finally figured out how to remount the touchpad cable lever by looking how the other lever was mounted. Next time instead of just pulling the ribbons out, I think I'll be a better technician and just flip the levers up like HP intended.

Below you can see the little white lever sitting off to the side for the touchpad ribbon cable.

Here I finally figured it out. This is really the only part of the job that gave me any grief. The missus even made it a point to remind me that she didn't use or care about the touchpad. But I wanted to put it back the way I found it. And besides, someday we could gift this machine to one of the kids or sell it, and the new owner I'm sure would want it functional.

Next, put back the 4 mounting screws on the metal plate. making sure to push around the edges of the cover, making it snap into place all the way around. One of the screws on the right side is recessed, so be careful not to drop it down into the case, or you could be repeating the hardest part of the disassembly.

Next, it's time to remount the keyboard. Now would be a good time to double check the other connectors, screws, etc. Unlike the black connectors with the white levers, the keyboard on mine has a white connector with a black lever, which confused me. Being old, I'm easily confused. Lift the lever, gently slide the keyboard's ribbon connector back in, and push the lever down. It should be nice and snug. At that point, just snap the keyboard in place.

Notice that the keyboard only has one mounting screw, accessible from the other side. If you wanted just to replace the keyboard, all you would need to take of is this single keyboard release screw, which is even marked on the other side.

NOTE: There are lots of leads on the keyboard's ribbon connector, so make sure it is lined up perfectly and snug before lowering the lever.

Next, the keyboard should just snap back in place. I forgot to blow the keyboard out with the can o'air before I snapped it back into place, so I did that right after. Probably not a big deal either way since the keyboard is so easy to get out. And just like the case cover, I went around the keyboard pressing firmly all the way around, making sure it snapped in place.

Next, close the lid and flip the laptop back over. We're almost done!

Remount the wi-fi board and put back the single mounting screw. I forgot to take a photo of it dismounted, so here's the same picture as above, which was actually taken after it was reconnected and remounted.

Reconnect the hard drive cable through the window. This is another one of those cables where you want to line it up perfectly and push it straight down, until it snaps into place.

Now slide the DVD drive back into place and put the single mounting screw back so the drive won't fall out on accident.

Next, put the keyboard mounting screw back so the keyboard will stay nice and snug.

Next, put all the other screws back which are under the sliding plastic cover. Remember that the mounting screw from the side cover does not come off the cover, so don't make my mistake and try to put a screw there. A couple photos above you can see the recessed area where the sliding cover screw goes in, right below the wi-fi board.

Double check that the screws are there, the DVD drive looks mounted right and the wi-fi card and hard drive data cable are mounted right, and put the plastic slide cover back. Then tighten the mounting screw.

NOTE: At this point I put in the battery, powered up the machine, and made sure it booted Windows. Next I checked that the touchpad worked because it gave me some grief. I tested the keyboard, too, and took out the battery. It does feel like it's moving warm air out the vent, but it's hard to tell. If I did this for a living, I probably would've bench tested the new fan before I put the whole thing back together. But in my home office, I don't know if the fan works until the laptop is in service long enough to heat up and start blowing warm air out the vent.

Next, I mounted the 3 screws in the battery compartment and remounted the battery itself.

At this point you should be looking at the remaining 8 case screws--put them all back. If you did everything right, you should have no screws left over.

Just for giggles, I did a final looksie at the whole machine, even picking it up and moving it around to make sure there wasn't anything loose, flopping around. Better to repeat the whole job than to buy the missus a brand new laptop, which she would take without complaint.

I thought about thoroughly cleaning the outside and windexing the screen, but this isn't my computer. My part is done, and the machine works perfectly! Hopefully if you followed along, yours works too!

A few years ago I wrote a CPU load tester app for Windows, and we ran it for 20 minutes trying to overheat the laptop. The original fan was probably defective from the factory, because this machine had a loud fan from day one, and doesn't anymore. I bought an Asus machine at the same time we bought this HP, and I've never heard the fan on it. The thermal grease also didn't look that great, so I'm thinking that this machine has superior cooling to when it was new. Hopefully it won't give us any more grief.

As someone who rarely does any work on laptops, I was rather proud of myself that the whole job took about 2 hours including the photography and writing the steps down as I did them. But it's not a race, so take as long as you need to. A warranty service shop would probably have it for a week or two. And just a regular shop would probably charge you $100, so as long as your finished product works, you're going to be ahead of the game!

Below is the faulty fan that started this whole adventure.