[NAME] , Dell original power adapter uses a chip and extra wiring, sending signal to the PC/Laptop to verify OEM status.  So when it had failed and not recognized by the PC/Laptop, you should get some kind of message at boot.  Although it would power on the unit but it will not charging battery (for laptop).  On both AIO and laptop, the processor will be limited to minimum performance.  You can verify the information provided with the symptom on your machine and determine if your power adapter is bad, then a replacement will bring back the performance.  You can test it with a different power adapter or verify the power status in BIOS before getting a replacement.  
My processor is i7-10510u. System is Dell all in one 7790. I cannot adjust the processor speed in Bios. It is constantly 0,41Ghz and that makes the system very slow. Somebody knows how to change. It was after an update Intel Corporation Extension 17.9.6.1019. I cannot remove this update anywhere. The processor speed is all the time 0,41Ghz. Hope somebody can help me with this. [IMAGE]  
Maximum core speed