Overheating CPU

My main desktop computer has been overheating under heavy load over the last year or two, mostly when gaming, or more recently during upgrades. It’s not a new processor – It’s a 2012 model that I installed in 2017 – but it’s continued to handle everything* I’ve thrown at it and still be responsive right up to the point where it shuts itself down to prevent heat damage.

It’s not a high-performance rig. It shouldn’t need a ton of cooling. So I checked the basics:

• There’s room behind it for hot air to escape.
• Airflow through the case isn’t blocked.
• It’s got an exhaust fan on the back of the case.
• All the fans spin, and speed up when they’re supposed to.

And did some maintenance:

• Cleared out the dust (and there was a lot of it) with compressed air.
• Replaced the thermal paste several times.
• Added two case intake fans, one at the front and one on the side.
• But…I failed to check inside the heat sink!

Every time I did this, it got the system back to the point where it would stay up during games, at least most of the time, and a few months later I’d have to clean it out again. (It’s not like I was going to buy a new CPU and motherboard in the middle of the 2021 chip shortage if I didn’t absolutely have to!)

Today I finally found the problem. By removing the heat sink and looking at it from the side instead of the top (which looked fine).

The space between the heat sink plates was completely clogged with dust! The cool air from the fan couldn’t get through, and only the outside could radiate heat!

It took a while to clear it out. I removed the CPU heat sink and fan, and fired bursts of compressed air through the sides until I could see through it clearly from either side and looking upward through the fan.

But now? The box is humming along at temperatures in the solid middle of its operating range, even stress testing it with multiple tasks that had made it spike up to well above max before!