Oberservation:
X1 Carbon 4th Gen runs very slowly. Task manager shows the CPU running at 400 MHz.
In rare cases (1 out of 20) it runs at normal speed.
It does so when running on battery or only with the charger.
When both are connected - charger and battery (50% charged) - the system switches between charger and battery once per second.
The laptop does exactly the same thing when running Windows or Linux, so OS level problems can be ruled out.
Flashing CleanME and a different BIOS made no difference.
Intel's XTU utility and ThrottleStop indicate a thermal problem and a power problem.
XTU shows PL1 at 15W and PL2 at 25W, which seems reasonable.
Turning off BD PROCHOT in ThrottleStop raises the CPU frequency a little bit, but does not solve the problem.
The charger works fine, I have tested two other chargers.
The board does not show any sign of liquid damage.
The fan is clean and produces a clean tacho signal (checked with an oscilloscope).
I checked ACDC_ID (the middle pin in the slim tip adpater) and its path to the MEC1653. Everything looks fine.
I measured the resistance of all the NTC resistors. They all have a resistance of 600 +- 50 Ohms.
All power rails are ok.
What else can I check?
schematics can be found here: https://www.badcaps.net/forum/showpost.php?p=955658
X1 Carbon 4th Gen runs very slowly. Task manager shows the CPU running at 400 MHz.
In rare cases (1 out of 20) it runs at normal speed.
It does so when running on battery or only with the charger.
When both are connected - charger and battery (50% charged) - the system switches between charger and battery once per second.
The laptop does exactly the same thing when running Windows or Linux, so OS level problems can be ruled out.
Flashing CleanME and a different BIOS made no difference.
Intel's XTU utility and ThrottleStop indicate a thermal problem and a power problem.
XTU shows PL1 at 15W and PL2 at 25W, which seems reasonable.
Turning off BD PROCHOT in ThrottleStop raises the CPU frequency a little bit, but does not solve the problem.
The charger works fine, I have tested two other chargers.
The board does not show any sign of liquid damage.
The fan is clean and produces a clean tacho signal (checked with an oscilloscope).
I checked ACDC_ID (the middle pin in the slim tip adpater) and its path to the MEC1653. Everything looks fine.
I measured the resistance of all the NTC resistors. They all have a resistance of 600 +- 50 Ohms.
All power rails are ok.
What else can I check?
schematics can be found here: https://www.badcaps.net/forum/showpost.php?p=955658