XPS 17 - Severe performance degradation after BIOS upgrade

I want to have this problem fixed. Dell advertised HK CPUs (including 12900HK) as unlocked and they actually were unlocked till the recent BIOS updates. Now Dell decided to change the embedded controller's firmware to lock the CPU and disable the feature we have paid for. As for the performance degradation, it's not in the first time.

Today I reran these tests with all the performance options enabled and got nearly the same poor score (12600 instead of 14500):

There's an obvious performance degradation after a BIOS update. Unfortunately, the Dell support team doesn't want to help me with this problem and calls it "normal behavior".

Here are the results before BIOS upgrade:

All the tests were made on the same device with the same cooling system and power settings. No additional apps are running.

The new BIOS update (1.14.0) includes the updated microcode from Intel. It completely locks undervolting and adjusts the V/F curve. As a result, the device consumes more power for the same performance level and/or shows less performance under the same power limits.

Unfortunately, Dell blocked the downgrade.

Hi there, TwistedAndy.

I currently have a relatively new Dell XPS 15 9520 (2022) and I recently discovered a drop in performance. When I run tests I use the optimized performance setting in My Dell settings and do not plug in the charger while running the test, I only was able to achieve scores of 780 single core and 5600 multicore and this is on a I7 chip. Is this normal? I was previously able to achieve scores a lot higher such as 7000. Although when I plug in the charger I am able to get scores of up to around 9000 and 10,000. When you achieved 14000 and 12000 on cinebench, did you have your dell charger plugged in and did you use max performance on My Dell?

I have contacted Dell support regarding the performance drop, and they told me that this is normal and the system works as intended.

I did all my tests in the Optimized mode with a plugged-in charger. You should get nearly 13000-14000 in 10 minutes Cinebench R23 MT test with the old version of BIOS. If you decide to update it, then scores will be lower.

The problem with the new BIOS is way more complicated. It includes a new "feature" from Intel called Intel Undervolt Protection and the new microcode. Unfortunately, Dell decided to keep it enabled by default. This is even more confusing, the classic undervolting through BIOS is also broken and works not as expected.

Has your performance changed is BIOS version 1.15.0?