Question Laptop CPU throttles down to 0.4ghz when plugged in, but runs normally when plugged out.

[BerzerkFlame]

HP Pavilion Laptop 15ec
Processor: AMD Ryzen 5 5600H with Radeon Graphics, 3.30 GHz
GPU: NVIDIA GeForce GTX 1650
8 GB RAM

This started yesterday, and earlier that day my laptop was running plugged in just fine, but the second time I opened it that day my CPU had hiccups of being capped at 0.4 GHz before going back to its normal speed for a few seconds or even pinballing between normal and 0.4 GHz constantly. I reinstalled all my drivers, restarted multiple times, reinstalled the battery, check my power plan settings to make sure those were normal, ran multiple antivirus scans, defragmented my disk and used chkdsk to see what any of these could be causing the sudden throttling assuming I changed absolutely nothing.

The last possible culprit appears to be something with the CPU's ability to draw power when plugged in, because as the title states I get normal performance, granted limited at speeds of 1.8 GHz, without being capped at 0.4 GHz when plugged out. Using CoreTemp, I seem to be getting 4W when plugged in, periodically switching to normal voltage, and whenever the laptop is plugged out I get the ordinary voltage I would need to run games or even some light software normally. When idle the laptop runs fine regardless. I seem to have tried everything that could pertain to the issue, so it might be that I have to replace my CPU which I'm trying to avoid since that would mean getting a new laptop even though everything else works fine including the battery itself.

 

[Lutfij]

Welcome to the forums, newcomer!

What OS are you working with at this moment of time? Since you're on an HP laptop, use your serial number on HP's support site to narrow down a bespoke support page for your laptop. Cross-reference your current BIOS version with the BIOS versions listed on support site and if you have any versions pending update.

 

[BerzerkFlame]

Im currently working with Windows 10, Ill look into the support site again but I looked there earlier and wasn't able to find anything particularly helpful. Thank you for the swift reply, though!

Edit: I updated my BIOS and the issue persists which I feared was the case, my CPU still only draws 4W when running loads it could normally run before when plugged in and functions normally when idle or plugged out running those loads.

Edit 2: I ran more diagnostics and fixes with HP's provided tools but the issue persists, and it appears to affect my GPU so I'm not quite sure what the exact culprit is but it seems to be an issue with power randomly taking dips.

Edit 3: Ran some more tests and looked up similar issues and it seems I’ve narrowed the absolute cause down to A: My CPU might be faulty and is throttling itself beyond repair by design or whatever or B: My laptop charger is faulty. I’ll get another charger and test it to see if that’s the case.

 

[Lutfij]

If the OS is the same installation as that when the laptop came out of the box, I'd try and backup any and/or all critical content off the OS drive, prepare a bootable USB installer using Windows Media Creation Tools and then proceed to reinstall the OS afresh.