Hey everyone! I have a Dell Latitude 7390 with an i7 8650U processor, and I'm facing a weird issue. When I'm not connected to the charger, my CPU is stuck at just 0.40GHz. But, once I plug in the charger, the speed jumps back up to normal. I've been troubleshooting this for a while, but nothing I've tried has worked. Here's what I've done so far: replaced the battery (which checks out as 'excellent' in the BIOS), swapped the CMOS battery, reset the RTC, applied new thermal paste, and confirmed that the CPU isn't thermal throttling. I've also updated the BIOS and drivers, reset the BIOS settings, rolled back to a previous BIOS version, did a clean install of Windows, disabled C states, and even turned off Intel SpeedStep and Turbo Boost—none of that helped. I love this little laptop, and aside from this issue, it's been great. Any suggestions?
2 Answers
You did a ton of troubleshooting! To confirm the CPU's behavior, how are you checking the speed? Are you using Task Manager? It's good to see the speeds change when you plug in the charger. That means the CPU is responding, but something's off with battery power.
Have you tried running Intel's Processor Diagnostic Tool? It might give you some insight into the clock speed when connected to both the charger and on battery. It's worth a shot!
I actually ran it on both power sources, and surprisingly, it passed and my CPU is performing normally now!
Yeah, I'm looking at Task Manager to monitor the speeds. It definitely jumps when I connect the charger, but drops right back down when I unplug it.