If that's the case then there are at least two race conditions that set this issue. Another way to create a white / orange flash is to enable xtu, boot into windows and create a new XMP profile for the LPDDR3. Laptop will shut down and refuse to boot, displaying the white /orange sequence. Performing the steps I've outlined above successfully clears nvram and laptop starts up again (without any of the necessary IFR settings to undervolt, boot macos etc).
If you're interested in experimenting with IFR and Bios flashing I could do with some help. I need to create a condition that allows modified Bios to be flashed by FPT without verified boot or boot guard. I've completed most of the steps but need to find a way to unlock the flash descriptor and most of the existing ways (pinmod, SPI, Bios) don't work on this machine due to a change in WSON chip and new board schematics...
The white orange flash in unbootable state was roughly at a 1-2 second pause interval, whereas the white orange flash booted from the the partially inserted battery was very rapid with almost no pause between flashes.
What is FPT? I assume the BIOS recovery somehow checks the signature of the renamed EXE before flashing. Maybe it just checks for integerity, id guess it also verifies with a specific Dell key. Maybe if you recompiled the bios exe with a modified ROM file with correct integrity checksum, got the bios into a unbootable state, the BIOS recovery might accept the BIOS_IMG.rcv based solely on the file integrity and not the dell signature. Sounds like a bit of a stretch but whatever state I got it in allowed me to flash a supposedly undowngradeable bios which is interesting because whatever signature it was supposed to look for to prevent downgrade it did not.
These variables from IFR.txt may be useful to you
Demo Board, Form ID: 0x27F0
Serial Port Console Redirection, Form ID: 0x27F5
Security Configuration, Form ID: 0x276F
Setting: BIOS Lock, Variable: 0x894
ME State, Variable: 0x2
AMT BIOS Features, Variable: 0x68F
ME Unconfig on RTC Clear, Variable: 0x1402
Me FW Image Re-Flash, Variable: 0x67A
Firmware Update Configuration, Form ID: 0x2790
Also I found someone currently attempting to modify the kabylake xps bios
https://www.win-raid.com/t3012f16-Help-with-BIOS-mod-for-Dell-XPS-Kaby-Lake.html
EDIT: I now notice that someone is you lol
When I bricked the bios I changed all the USB C variables, and both the active trip points down 1 step each, enabled XTU/WDT and disabled CFG lock. Im not sure which variable bricked it (I was foolish to have changed so many at once).
I am very interested in playing with more IFR variables. I just upped the CPU/GPU undervolt to -.1 volt each (0x64)
It runs stable, with almost no performance increase compared to .-05. However it seems to cause the wifi card to be unrecognized after prolonged sleep, and I think it degraded the bluetooth quality. I was using a bluetooth speaker I've used with it before last night and the range was terrible. I also was playing a bit with clover so I will have to test it compared to it's sister XPS and set it back to -.05 to know for certain.
The variables I'm most interested in playing with are
Memory Voltage, Variable: 0x6AA
DIMM profile, Variable: 0x7B7
Option: Custom profile, Value: 0x1
Option: XMP profile 2, Value: 0x3
Active Trip Point 1, Variable: 0x2AD
I really want to make the fan turn on sooner, the default value says trip points are about 55 and 71 degrees celcius but intel power gadget will report 70 degrees with zero fan response. If I'm really multitasking it idles around 60+ with the whole bottom plate hot and the fan silent which is unacceptable. Under benchmarking the CPU hits 99 but the fans keep the bottom cool, which means the rest of the hardware cool.
Try to find out which thermal zone directly refers to the processor as described above. A low value for passive should avoid fan activity but may slow down your machine if it exceeds the trip point's limit. The throttling is done by the kernel itself, the maximum throttling variable is not used in case of the passive limit is reached. Increase the active trip points values (if supported) to additionally avoid fan activity.
My primary goal is to increase hardware lifespan by reducing heat. I also want to get the SDcard slot working.
Im considering changing the second thermal trip point again but if its a guaranteed brick I dont want to push my luck. The IFR.txt declares the various trip point values so it seems built in.
What do you think?