[request] unlock TDP advanced options in HP spectre x360 with 8550u


I’m glad to find this forum with so much information and support.

I have a HP spectre x360 with a i7 8550u. This CPU supports a TDP up to 25 W, however it seems to be locked in this laptop at 15 W, despite my temperatures being low during a stress test and the fan being not even at full speed. This feature bottlenecks significantly my eGPU.

As far as I now the only way to increase the TDP is in BIOS. Unfortunately, these settings are hidden in my BIOS (AMI).

I found over the internet many people claiming the same problem, but no one reporting a solution.
So I would like to mod and flash the BIOS to unlock the TDP settings, and make a proper report/guide so that others with the same laptop could benefit.

But I need your expertise and guidance to do it.

1) first, is what I’m asking even possible in this laptop? is there any problem related with RSA?

2) in a first attempt I created a flashing USB drive using the HP flashing utility (083B9F24.EXE), it created a *.bin and a *.sig file (083B9.bin and 083B9.sig), then I modified the *.bin file with AMIBCP64, and I tried to flash the modified BIOS, but I get an error saying that it couldn’t open the signature file (of course, it cannot be so simple), any way to overcome this? should I use other method, such as booting in DOS and use AFUDOS to create an .rom file and then modifying and flash it?

I would appreciate very much some advice.


Hello there, if you are still trying to increase the tdp, I have found a solution on my hp cs0000ne. Basically it is impossible to control the tdp limits from bios as it is controlled by EC. However, you can fool the EC into reporting a false power consumption. Basically, you wanna edit your ifr until you find a variable called IMON Slope. There should be four of them. edit each one and set the value to 32 in ru.efi or h20uve(or 0x32 if you are using efi shell) . This will fool the EC into thinking its using half of the power it is really using. And my god this cpu is a freaking beast. After undervolting -140mv(I got pretty lucky u probably wont be able to reach this low) I was able to indefinitely run at max turn frequency of 3.7 ghz. And the best part is, it never exceeded 83 degrees.(your cooling performace may vary)

EDIT : I have written a detailed guide here

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thank you so much for this help
I don’t use no more this PC
but I’m sure your findings and detailed guide will help many people
or even me in the future, since your guide seems to be valid for modern CPUs

have a nice day