i7-8750H: Intel XTU applying wrong default PL1 on startup

[LRunt]

Hello everyone,

I recently bought a Dell XPS 15 9750 with an i7-8750H. I used XTU to undervolt it, which worked fine, but recently I noticed in HWMonitor that the PL1 changed from 56 W to 12.5 W, resulting of course in quite a bit of power throttling during load. I have a custom profile which has it set to 56 W and when I apply that, everything works fine. But every time I restart the PC, the PL changes to 12.5 W again. The default profile actually shows 56 W as well, but when I select it and press "show values", it changes to 12.5 W, which shouldn't be possible, because the default settings were 56 W until recently. Does anyone have an idea what could have caused this and how to fix it?

[idata]

Hello Fatality_Yoda,

Thank you for posting on the Intel ® communities.First, I would like to begin by saying that altering clock frequency or voltage may damage or reduce the useful life of the processor and other system components, and may reduce system stability and performance. Product warranties may not apply if the processor is operated beyond its specifications. Check with the manufacturers of system and components for additional details.The system manufacturer (in this case Dell*) should be able to assist you further on how to optimize your system and work with it in the best way. However, as mentioned above, due to possible stability issues it is not recommended by Intel to do so. Regards,David V Intel Customer Support TechnicianUnder Contract to Intel Corporation

[idata]

Fatality_Yoda: I just wanted to check if the information posted previously was useful for you and if you need further assistance on this matter?

Regards,David VIntel Customer Support Technician Under Contract to Intel Corporation

[LRunt]

Thank you for taking time trying to help me. In the end, how I fixed it was by booting with C-states disabled in the BIOS. Then, the PL1 was the correct 56 W, which stayed like that even after re-enabling C-states again. So I guess the processor was stuck in a certain low-power C-state. Now I am using ThrottleStop to undervolt which works great.