[SOLVED] Cleaning GPU Heatsink - Compressed Air 70 psi

InvalidError

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Hold your finger on the fan so the fan blades dont spin. Its a good way to over spin the bearings and wear them out.
The real danger of over-spin isn't bearing damage, that will take a while to do any meaningful wear unless the bearings are complete garbage or already shot. It is back-EMF into the coils frying the BLDC circuit since induced voltage is proportional to speed and the electronics will fail at 20-35V (2-3X over-speed) depending on how overbuilt the circuit is.

I was more worried about it not being enough pressure, so it's safe to say it will get out the hardstuck dust bunnies?
Canned air/propellant should be able to get most stuff out but caked-on clumps may require mechanical cleaning such as using a discarded toothbrush.
 
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Vellaura

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Hold your finger on the fan so the fan blades dont spin. Its a good way to over spin the bearings and wear them out. You can also hold the can back a little bit, it will cut down on the pressure being blown into the card.
Hello! Thanks for the reply and reminder on the fans, however I was more worried about it not being enough pressure, so it's safe to say it will get out the hardstuck dust bunnies?
 

InvalidError

Titan
Moderator
Hold your finger on the fan so the fan blades dont spin. Its a good way to over spin the bearings and wear them out.
The real danger of over-spin isn't bearing damage, that will take a while to do any meaningful wear unless the bearings are complete garbage or already shot. It is back-EMF into the coils frying the BLDC circuit since induced voltage is proportional to speed and the electronics will fail at 20-35V (2-3X over-speed) depending on how overbuilt the circuit is.

I was more worried about it not being enough pressure, so it's safe to say it will get out the hardstuck dust bunnies?
Canned air/propellant should be able to get most stuff out but caked-on clumps may require mechanical cleaning such as using a discarded toothbrush.
 
Reactions: Vellaura

Vellaura

Great
Nov 30, 2020
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The real danger of over-spin isn't bearing damage, that will take a while to do any meaningful wear unless the bearings are complete garbage or already shot. It is back-EMF into the coils frying the BLDC circuit since induced voltage is proportional to speed and the electronics will fail at 20-35V (2-3X over-speed) depending on how overbuilt the circuit is.


Canned air/propellant should be able to get most stuff out but caked-on clumps may require mechanical cleaning such as using a discarded toothbrush.
That was a very scientific explanation, just so I understand correctly, did you mean that overspinning the fan isn't what breaks it, more so that your pumping more power into then it needs to have?
 

InvalidError

Titan
Moderator
That was a very scientific explanation, just so I understand correctly, did you mean that overspinning the fan isn't what breaks it, more so that your pumping more power into then it needs to have?
When you blow through a fan and spin it, it behaves like a wind turbine: the fans' permanent magnets spin around its coils, which generates voltage proportional to speed across them. If that voltage exceeds the drivers' reverse breakdown voltage, the electronics may get damaged.

The only power that gets "pumped" into it (assuming the system is turned off while cleaning) is the power the fan generates from getting spun. If the fan was designed with diodes that clamp coil voltage to supply rails (basically regenerative braking for over-speed protection), you can light LEDs by spinning the fan fast enough. That would be another reason to prevent the fan from spinning too much while cleaning - don't want it to generate enough power to potentially damage stuff.
 

Vellaura

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When you blow through a fan and spin it, it behaves like a wind turbine: the fans' permanent magnets spin around its coils, which generates voltage proportional to speed across them. If that voltage exceeds the drivers' reverse breakdown voltage, the electronics may get damaged.

The only power that gets "pumped" into it (assuming the system is turned off while cleaning) is the power the fan generates from getting spun. If the fan was designed with diodes that clamp coil voltage to supply rails (basically regenerative braking for over-speed protection), you can light LEDs by spinning the fan fast enough. That would be another reason to prevent the fan from spinning too much while cleaning - don't want it to generate enough power to potentially damage stuff.
okay gotcha, basically, don't let the fans spin :D
 

lvt

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I managed to clean the fan easily since its out in the open to reach, just inside the heatsink area is hard to reach without pulling it apart.
How old is your computer?

If it's like 5 years old or older, you should remove the entire heatsink + fan assembly, remove the fan to clean them separately. Wipe the CPU clean and apply a new layer of thermal paste.

Personally, for any system that is older than 5 years old, I remove averthing and clean them with warm water from a hose, including case and PSU.
 

Vellaura

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How old is your computer?

If it's like 5 years old or older, you should remove the entire heatsink + fan assembly, remove the fan to clean them separately. Wipe the CPU clean and apply a new layer of thermal paste.

Personally, for any system that is older than 5 years old, I remove averthing and clean them with warm water from a hose, including case and PSU.
I have a gainward gtx 970 blower edition. pretty old, i would be down to do a deep clean but I honestly don't want to risk breaking something considering how hard it is to find a gpu these days and how expensive they also are. My temps are perfectly fine, i get 30c on idle. I'm just a bit of a clean freak, dust bothers me.

I was told by a friend that something as small as overtightening a screw can break a gpu, I dont know how sensitive or durable they, don't want to take any chances.
 

InvalidError

Titan
Moderator
If it's like 5 years old or older, you should remove the entire heatsink + fan assembly, remove the fan to clean them separately. Wipe the CPU clean and apply a new layer of thermal paste.
I wouldn't bother taking apart a GPU to replace paste unless there is a thermal throttling issue. While the OEM paste may not be the highest-performing stuff imaginable, it usually is tried-and-true stuff like zinc or aluminum oxide in silicone oil that is chemically stable indefinitely under normal conditions and will continue doing its job fine as long as you leave it alone.

I was told by a friend that something as small as overtightening a screw can break a gpu, I dont know how sensitive or durable they, don't want to take any chances.
The main danger is uneven tightening since that puts extra stress on one corner of the GPU die and can easily crack it.

If it ain't broke, don't fix it. Especially when you cannot get anything comparable for a remotely reasonable price right now.
 
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Vellaura

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I wouldn't bother taking apart a GPU to replace paste unless there is a thermal throttling issue. While the OEM paste may not be the highest-performing stuff imaginable, it usually is tried-and-true stuff like zinc or aluminum oxide in silicone oil that is chemically stable indefinitely under normal conditions and will continue doing its job fine as long as you leave it alone.


The main danger is uneven tightening since that puts extra stress on one corner of the GPU die and can easily crack it.

If it ain't broke, don't fix it. Especially when you cannot get anything comparable for a remotely reasonable price right now.
Yeah definitely, which is why i'm just going to get a can of compressed air and clear out the dust bunnies blocking airflow.

I also read the thermal paste on a gpu never really needs to be changed throughout it's lifetime unless you are experiencing some significant/specific issues, not sure how legit that information is though.
 

InvalidError

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I also read the thermal paste on a gpu never really needs to be changed throughout it's lifetime unless you are experiencing some significant/specific issues, not sure how legit that information is though.
Chemically stable pastes don't need to get changed. Ever.

When the paste "stops working", it is usually because the heatsink got nudged and the paste layer got broken up. Since GPU heatsinks are clamped to the board using four screws directly around the GPU and a dozen more around the rest of the PCB, that hardly ever happens. It is more common with CPUs that have only two or four mounting points and have a much taller aspect ratio that give extra leverage for nudges to break the "cured" paste layer.
 
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Vellaura

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Chemically stable pastes don't need to get changed. Ever.

When the paste "stops working", it is usually because the heatsink got nudged and the paste layer got broken up. Since GPU heatsinks are clamped to the board using four screws directly around the GPU and a dozen more around the rest of the PCB, that hardly ever happens. It is more common with CPUs that have only two or four mounting points and have a much taller aspect ratio that give extra leverage for nudges to break the "cured" paste layer.
Awesome, this has been quite the learning experience. Thanks all :)
 

Karadjgne

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My biggest concern when using canned air is two-fold.
First, it's freezing cold and that can have a serious affect on things like motherboards when concerning sensitive components, so don't stick the straw up very close and hold it there for too long.
Second is related to the first, but not by temp. It's 70psi coming out a very small appature, and things like gpu fan blades are not exactly wonders of strength. It doesn't take much pressure to break them and canned air has that pressure.
 

Vellaura

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My biggest concern when using canned air is two-fold.
First, it's freezing cold and that can have a serious affect on things like motherboards when concerning sensitive components, so don't stick the straw up very close and hold it there for too long.
Second is related to the first, but not by temp. It's 70psi coming out a very small appature, and things like gpu fan blades are not exactly wonders of strength. It doesn't take much pressure to break them and canned air has that pressure.
It will be going through the heatsink, so not much on delicate parts.

As for the second point....i'm not sure.
 

Karadjgne

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The bigger the fan, the stronger/thicker the blades need to be in order that the pitch of the blade not change with momentum and rpm. It's why Noctua took forever to create a 200mm Fan, they couldn't get the composition of the plastic to their standards and not have a giant hub.

Gpu fans have tiny hubs, for a 60-80mm fan and still have enough blade area to actually move air and enough static pressure to push that air across a heatsink, so the blades as a result of such weak motors must be extremely lightweight in comparison.

This makes them fragile, much more so than a case fan. The sheer amount of posts online asking if they can glue the fan blade back on after they broke it cleaning the gpu is hilarious.
 

InvalidError

Titan
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the blades as a result of such weak motors must be extremely lightweight in comparison.
The weight of fan blades does not have much to do with it, most of the power goes into aerodynamic drag and pressure changes. If you made dimensionally exact replicas using plastic and tungsten, the only major difference between the two would be the heavier fan taking a few seconds longer to change speed due to inertia but would ultimately reach the same speed under identical load minus a small amount from additional bearing losses.

Most fans today are made from plastic mainly because plastic is cheaper to manufacture in all sorts of shapes.
 

Karadjgne

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Motor life and power use. Heavier fan blades take more amperage/heavier duty motor to startup and when even slightly out of balance will wear on bearings at a higher rate than lighter blades. Gpu fan motors tend to be tiny compared to case fans of equitable size, and spin at higher rates. The longer the blade, the stronger the motor need to be

And while aerodynamic drag induced by blade pitch is a major factor, weight is also a consideration in balance and strength (the amount of plastic used for the blade) so that pitch doesn't change in proportion to rotation and drag. Like adding weights to a car wheel to keep it from tearing up the hub bearings.

But gpu fans are cheaply made, not a lot of R&D usually put into their design.
 

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