How to diagnose occasionally freezing computer

Question

The problem

I have a desktop computer running Windows 10. Since about 1 year, I have been experiencing occasional freezes where the computer stops responding and has to be reset manually. I've tried waiting for a few hours once and it didn't recover on its own.

Observations

The first thing I've checked is the memory. I've tested the memory with MemTest86 and found no errors.

The event viewer also doesn't contain anything relevant.

One thing I've noticed is that this seems to happen more frequently when the ambient temperature is high. Now that it is summer, and the ambient temperature in my office is almost 30ºC, it seems to be happening more.

In the winter, the computer froze more frequently while playing video games or while encoding video, although it sometimes freezes while doing lighter tasks. I've tried updating the video drivers, and also installing older versions, but that didn't seem to help.

The last suspicious thing is a USB hub that I have that sometimes has a bad contact. If I touch the wire, the devices that are connected to it are reset, but the PC itself seems fine.

What I tried

I tried monitoring the system with OpenHardwareMonitor and checking the sensors from a different computer (using the HTTP interface) but couldn't see any strange values when the computer freezes.

I also ran some stress tests with MSI Afterburner / MSI Kombustor, but couldn't get the computer to freeze while the tests were running.

Monitoring the sensors and doing a CPU stress test causes it to reach high temperatures, but the system remains stable:

Since the CPU is being stressed, I suppose it is expected to reach such high temperatures. During a warm day and normal usage, the CPU temperature remains around 60ºC.

Here's the main hardware:

• CPU: Intel Core i9-9900K @3.60 GHz
• Graphics: NVIDIA GeForce RTX 2070 SUPER
• Motherboard: MSI MPG Z390 GAMING EDGE AC
• RAM: 2x 32Gb Corsair DDR4-2666 in slots 2 and 4

What can I do to identify the cause of the freezes?

Edit

Today the PC froze again, and I was monitoring it from another PC using HWINFO. Here are the last values from the sensors. I can't see anything suspicious here:

Answer 1

You have performed commendable testing. You've also noted the issue seems to be related to heat, both environmental and due to high CPU and/or GPU load.

1. Confirm that it is heat. Use a tool such as HWinfo or an alternative to check CPU and GPU temperatures.

2. It could be heat ids affecting another component, such as a marginal power supply. You might try gently warming the PC with a hair dryer to see if that causes "freezing" (hmm... odd inversion of meaning).

3. Have you (or someone else) made any changes, such as overclocking, that might be causing overheating? If so, roll back somewhat. Note that HWinfo also displays system timing, voltage and other settings in great detail.

4. Carefully clean everything, particularly heat-sinks and fans. Though some recommend removing CPU and GPU, reapplying thermal compound and reinstalling, there are many posts online on how to repair damage done by doing that procedure (and they often involve replacing expensive parts) -- I'd avoid trying that "repair".

5. If after all this, the system still is affected by heat, consider substituting an alternate power supply. Borrow rather than buy, since it might not be the cause.