On a Budget: Fixing my ACER V3-731 Thermal woes

Don’t buy a new one – just fix it up!

The thermal design of Electronics is very important. Electronic parts get hot. The resistance of materials results in heat. Nothing in modern mass-produced products gets much hotter than the CPU in a PC. It’s simply the sheer size of the circuits on the die, billions of transistors switching at insane frequencies, fighting against the resistivity of their locality, all made worse by parasitic capacitance. Energy wasted – energy transformed into heat!

My trusty big lump of a laptop started spending a lot of time with the cooling fan on at full speed and was getting quite hot during even moderate CPU load. I eventually got fed up with getting cooked, and bit the bullet, ordered some CPU thermal paste, and a fresh can of air duster.

My plan was to strip it down and remove all the dust, dog hair, and biscuit crumbs clogging up the innards. I’d read that CPU thermal compound can dry out and reduce efficiency over time, so I would strip it right down to the CPU, making everything shiny, and start again. Since this laptop is three or so years old, and still acceptable with Windows 10, it was worth making better.

First step: Gather the tools

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Air duster, cotton tips, spudger, Philips and flat screwdrivers, thermal paste, and spatula. Don’t forget the ESD work surface, wrist strap, Oh, and a fine needle. We’ll need all these things. A large bottle of Isopropyl Alcohol is not shown.

Make it safe to work on

I shut the machine down completely, no hibernation or standby for me. Flipped out the battery, and put it to one side.

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Flip the orange switch and out it pops!

Remove all of the things

I like to pull out as much as possible right at the start and put them aside for safekeeping. The more pieces you can remove the better.

In this case, removing the optical drive was non-optional. Unfortunately in my haste to shut the machine down, I neglected to eject the drive. This was not an issue; I simply inserted a fine needle into the manual eject hole to see on the right. After that, removing the drive was simply a matter of pulling on the DVD sled, the whole thing came away in one piece.

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The eject button is electronic, so only works when the power is on. Manual eject effected by overriding the locking latch with the hole bottom right.
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Gently pulling the drive tray, to disconnect the drive assembly from the motherboard connector. No screws, no wires, no fuss.

For this laptop, there are a few upgrade options, so a separate bottom panel (with sensible captive screws) can be removed. This reveals the memory slots, wireless card, GPU upgrade slot, and not one, but two hard drive slots. This is a big laptop, with a 17.1″ screen, so plenty of space inside for extra toys.

The next task was to pop out the hard drive, RAM DIMMS, and wireless card and set them aside somewhere safe (and ESD safe too!)  We don’t want to damage them accidentally.

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Some people insist laptops can’t be upgraded. This one can.

A word of caution regarding flying wireless wires, with dinky little micro RF coaxial connectors – don’t pull them off with the wires. If the crimping is not up to standard you’ll weaken or even rip off the connection. Then you’ll have a bad day. Merely prise under the connector gently, with a spudger, and it will pop off.

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The correct way to remove a micro RF connector – not touching the wire at all.

Unscrew all the screws

I find it hard to work out which screws to remove and which not to when doing partial disassembly. In this case, it was a total strip down, so I removed all the visible screws in the case’s lower half, making notes as to the number and size/type of each one, and where it came from. Trust me, make notes now, and save the pain later. There were only three types of screws in this case, so it was quite painless. Well done Acer.

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Two sneaky, flat, and incredibly short screws hiding under the optical bay.

Disconnect the cables to the mainboard

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LCD / LVDS Cable. Check.
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Flat or ribbon cables. Remove these by flipping up the locking tab (the little white tab on the socket body) with your spudger. Never pull the cable – it is ZIF (Zero Insertion Force) and is clamped in place with the tab.

Remove the track-pad and keyboard assemblies

The plastic around the trackpad was not held together with screws, just plastic clips around the edge. Careful application of the spudger around the join between the upper and lower parts all the way around the left, bottom, and right edges a little at a time was needed. The application of a little pressure and a bit of a wiggle allowed me to slide it along till the assembly came away.

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Exactly the same deal with the keyboard assembly. There were a couple of screws holding the keyboard down to the mainboard. Another ribbon cable was removed, and the keyboard was removed to reveal the whole mainboard.

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Keyboard connector

In order to get the mainboard out, before removing the screws, I peeled back the fabric cover over the LED bank.

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Be careful with this. It’s sticky, and if you peel it off and put it aside, and fluff sticks to it, it’ll be less sticky for when you try re-apply it later.

Removal of the remaining screws will free the mainboard from the clutches of the case.

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Same deal. Make a note of all the screw locations.
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Don’t forget this sneaky little screw. The fan is firmly attached to the CPU via the heat pipes, and really won’t move!

It’s Free!

So, once a thousand or so tiny screws have been located and removed, I got this far. A naked laptop. It was evident that it wasn’t generally too dirty, and a bit of a clean-around with the air duster and some IPA got all the dust and grime off.

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Swabbing around with a cotton bud soaked in IPA. Some of the ports were sticky! Not sure what was spilled here, but I don’t want it hanging around.

Carefully, Clean the fan impeller

Using the air duster to blast the bulk of the dust out, proved that the main problem was the heat exchanger end of the heat pipe (the far left part of the fan body) was clogged with dust and dirt.  The impeller blades were pretty dirty too. I was careful not to allow the fan to spin too fast using the compressed air can, so as not to cause bearing damage. I found it sufficient to just stick a finger on it, and spin it a little by hand as the air duster did the heavy lifting.

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Gentle squirts at the impeller to remove the bulk of the dust.
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My theory was that if it got wiped over with solvent, any stickiness would be removed and dust would not stick so well in the future. Time will tell. Anyway, it’s cleaner now.

Disconnect the fan & heat pipe

This was pretty straightforward, just remove the fan connector, and remove the CPU cooler screws in the order 1-2-3-4.

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Removed (and reassembled) in the order 1-2-3-4. I’m unsure if this was exactly correct, but I had no issues. The order is purely to enforce tightening of the diagonal screws first to prevent stress on the edge of the die and keep the thermal paste in place anyway.
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And it’s free.

Reassembly is the reverse of disassembly

Reapplying thermal compound is simple. I just wiped/scraped off the old stuff, and cleaned away the residue carefully with a cotton bud soaked in IPA, being very careful with the exposed CPU die!

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Whilst the CPU die is flip-chip mounted (active circuits and IOs pointing down) onto the package substrate, you still want to be really gentle with this. Silicon is very brittle. Just make it clean, and shiny and leave it be.
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Clean up the copper on the heatsink to remove all traces of the old compound

Apply the thermal compound

Sometimes called thermal grease, this stuff is more like a liquid gasket material. It is very thermally conductive, being loaded with particles of silver and other thermally conductive materials. Its job is to flow into all the little gaps and maintain intimate contact between the CPU die and the heat sink end of the heat pipe. It doesn’t set hard, is very sticky, and allows the thermal contact to be maintained as the various components expand at different rates as the CPU temperature varies. It is wise to do some research and buy a specialist, high-performance compound for this very demanding job. The stuff I used is a cheaper Chinese copy of a Japanese product whose name escapes me, but had good reviews during testing, and wasn’t terribly expensive.

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Tiny little syringe, but you don’t need much

I applied a generous blob, direct to the CPU die, and spread it into a consistently flat layer. I didn’t worry too much, as the excess will leak out the sides. I made sure to cover every bit of the die, so there could be no hot spots.

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Eugh it’s all sticky.

Screw the CPU heat sink back on

From this point on, it was pretty easygoing. I made sure to drop the heatsink back on square, so as to not disturb the thermal goo too much, then simply tightened the screws in the marked order 1-2-3-4.

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Tightening the screws 1-2-3-4. Diagonals first, or you will regret it!

Reassembly complete: Testing

I forgot to take a screenshot of the temperatures the CPU was getting to during light usage, but let’s just say 60 Degrees Celsius is far too hot. After reassembling the laptop, in pretty much the reverse order as above, I was rewarded with much lower core temperatures. Shown is at approx 50% CPU load, during light web browsing. Consequently, the cooling fan was operating at a very low speed and was almost inaudible. No more scorched thighs for me.

Cool running

Final Thoughts

Funny how things catch up with you isn’t it? It wasn’t even a whole month before the keyboard started to fail! I’m pretty hard on keys, and having hammering away without a care for the last few years, there were groups of them starting to not register presses. This resulted in some very strange comments from friends until I realised what was going on.

Had I the forethought (or had it started failing slightly earlier) I would have replaced the keyboard assembly whilst I was inside the laptop. Sadly, less than a month later, it was in pieces again to replace the keyboard. It’s quite an easy fix, and not expensive to buy via eBay. Still, you live and learn, don’t you? Perhaps, If someone reading this is attempting the same – it might just be worth your time popping a new keyboard in whilst you have the case open eh?

Just a thought.

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