Cleaning a CPU

While ordering parts for my new energy efficient server, I ended up buying a second hand I7 9700K processor.

When the piece had arrived, I was surprised to see a chunk of dirt that was burnt in, seemingly connecting some contact points together. I was worried that this would cause a short circuit and damage the CPU.

Analysis

I found that the shape of the dirt was different from what it seems on the first picture.

Upon closer inspection, using a digital microscope, the dirt seemed to be a bit more loose and some discolouration became visible.

On this second picture you see more discolouration and one contact that's almost completely covered in dirt.

Cleaning

What not to use?

After some research, I found out the following:

• Don't use any liquid that corrodes the metal
• Don't use any liquid that leaves a residue
• Don't use any liquid that evaporates too slowly
• Don't use a material that can leave behind residue

So what can you use?

• I found that isopropyl alcohol is a good choice. It's a solvent that evaporates quickly and doesn't leave any residue. It's also used to clean electronics. I use Isopropanol 99.9% Isopropyl Alcohol 2-Propanol 250ml in Glass Bottle.
• Cotton swabs are a good choice. They are small and don't leave behind any residue.
• Toothpicks are a good choice. They are small and can be used to scrape off dirt.
• A plastic scraper can also be helpful to scrape off dirt. Be sure to remove any particles that might break off.
  • I happened to have this glue remover lying around. While it's not ideal, it's better than using a metal scraper.

danger

I'm not responsible for any damage you might cause to your hardware.

The process

There is always a risk that your hardware stops working. I would recommend to only clean your hardware if there is a good reason to do so.

Rubbing

Cleaning with isopropyl alcohol and a cotton swab

danger

Be careful not to touch parts in the center of the CPU, as some components may be sensitive to static or alcohol.

1. Dip the cotton swab in the isopropyl alcohol
2. Gently rub the dirt with the cotton swab
3. Repeat until the dirt is gone

In my case, the dirt was pretty persistent. I had to use something with an edge to scrape it off.

Scraping

4. Use a toothpick or plastic scraper in a gentle motion to scrape off the dirt.
5. Use the cotton swab to remove any material that might have broken off.

Rubbing again

After scraping off the dirt, I used the cotton swab again to remove any residue.

6. Dip the cotton swab in the isopropyl alcohol
7. Gently rub the dirt with the cotton swab.

This is a video of what it looked like for me:

As you can see in the video, the dirt isn't completely gone. However, this should be clean enough to get it working without short-circuiting.

Drying

Some alcohol may have seeped into the CPU. It's important to let it dry before installing it.

8. Wait 15 minutes to make sure the CPU is completely.

Testing

9. Install the CPU, apply thermal paste and install the cooler.
10. Boot the system and check if it works.

In my case, I installed the CPU, and it worked without any issues.