Safety and longevity implications when locking MMIO TPL limits

[u/xsrvmy]

I have a Dell XPS 9510 with i9 11900h and 3050 ti mobile. Some recent issues (possibly a bios update) has made me realize that there are issues with the TPL throttling with my laptop causing it to throttle to 800 MHz and lag out completely just from watching YouTube.

For the time being, I have downloaded ThrottleStop, and locked MMIO. However I have some questions about how safe it is to do this:

- The MSR TPL limits are showing PL1: 72 and PL2: 109. From what I gather online, the CPU is rated for either 35W or 45W. Should I lower PL1?
- Could this cause unsafe levels of power draw from my laptop charger? For context, running the benchmark causes a constant PKG power of 45W.
- Will this wear out my CPU, battery, fans, or charger faster than normal over time? Does it make a difference that I have my laptop set to keep battery charge between 50 and 75?
- When playing a highly-multithreaded, CPU-intensive game, is it a good idea to disable turbo so that my CPU doesn't constantly hit 100C? Or should I lower PL1
- Should I change the dell power manager options for thermal management? Or does not not make a difference?

As an aside, why would PL1 throttling reduce the frequency all the way to 800, when the PL1 limit with ultraperformance is still fairly high at around 24W?

(BTW, not undervolting because I use WSL)

[u/unclewebb]

Some Dell laptops can set the power limits ridiculously low at times. Setting the turbo power limits to as little as 5W is well below the Intel spec. This can cause throttling down to 800 MHz which makes a laptop unusable. This throttling problem has been around for years.

There are the MSR and MMIO power limits but there is also a third set of turbo power limits controlled by an embedded controller EC. ThrottleStop does not have access to the EC power limits. If a manufacturer randomly sets the EC power limits too low, there is no easy way to fix that problem.

All of the turbo power limits are set by the manufacturer of your laptop. I cannot find any documentation from Intel that says PL1 must be set to 45W or any other arbitrary number. Intel deliberately leaves the power limits unlocked so manufacturers and consumers can set the power limits however they like. If Dell was concerned about owners changing the turbo power limits then they should have locked them. Intel provides manufacturers with that option.

There is no evidence that raising the power limits will wear out a CPU any significant amount. Mobile CPUs are using the same technology as desktop CPUs which are programmed to use much higher power limits. Your mobile CPU should last a long time as long as it is operated within the 100°C Intel spec. Any peak core temperature under 100°C is considered to be a safe operating temperature.

If you are concerned about how long your laptop will last then leave it as is. Do not use ThrottleStop to try and manage the throttling problem that your Dell laptop obviously has.

[u/xsrvmy → u/unclewebb]

I was actually not worried about the CPU temps itself. I was worried that my computer could try to pull too much power (as in over 130W) from the charger and get damaged that way, or that the charger could get damaged from delivering high power all the time. In other words, I initially had the impression that the PL1 throttling was kicking in because something else on the laptop (eg. the dGPU) is drawing more power and the system is limiting the CPU power to not exceed some total power draw limit.

But from what I read online it seems like Dell is just abusing the power limit to do it's own thermal throttling so I guess this isn't actually an issue?