How often should I replace the thermal paste on my GPU?

It's generally unnecessary to replace GPU thermal paste unless you notice higher temperatures that can't be explained by dust build-up or changing ambient temperatures. Typically, you shouldn't need to touch it unless something's off.

Maybe think about replacing it every 8 years? It's not something that needs regular maintenance unless you start seeing troubling temperature changes.

In my experience, I've had previous computers last well beyond 10 years without needing to change the paste, especially if you used a quality paste to begin with. No reason to worry unless something goes wrong.

The lifespan really depends on how hot your GPU gets. If it's running hotter over time, then yeah, the thermal paste can degrade faster. As a rule of thumb, if your idle and running temps are normal, you don't really need to mess with it.

You really don't need to worry about it unless you have thermal issues. Most thermal paste lasts for many years, so there's no hard rule on when to replace it. Even for CPUs, it can go for years without needing to be reapplied.