incendery

fantastic post very well written, thanks for your insight into this one 🙂

incredible work! love it 🙂

You're badgering them about a 10 year old barebones laptop during likely a somewhat busy Easter period, have some respect for people busy at work please, the world does not revolve around your laptop wants and needs.

"Anyway, by trying to fix it, you'll learn many things. 🙂" very well said 🙂 this is the best way to learn

at minumum to POST you will need CPU, GPU and one stick of ram. POST stands for power on self test. the EC bios can be flashed I believe it's stored on an 8pin flash like the main bios on these machines, sourcing a file is a different story I'm not sure with that 😬 maybe someone else here with a p870 can provide one.

A small update for tonight before I can do a full writeup with more testing. The current limit modifications have been a success!! I am able to pull 130W from the CPU sustained on a heavy avx load which would previously shut the laptop down immediately. I have yet to set up my MCU to convert the fan control signal so they are both running at 100% (good cooling but loud! 😅) I will do a thorough breakdown of the process once I have done more testing but I am so far very happy with the results

thanks! It's been a while since I played with the bios modifications and there was some back and forth getting all the drivers to work properly, I've attached a bios I modified for another user here for the p775tm1g (z370) this should work with your rtx3080 out of the box. for my own machine I am using the z370 derived Dsanke bios (that person is a wizard and I am in awe at their skills) which I have tweaked with the board ID changes and also fixed the audio driver bug due to mismatched IDs P7xxTM1-0729-9900KS_BoardID7715_3080 NvdGPUDxe_audiofix.7z

I missed another component which needed changing, PR162 must be changed to 27k

check page 110~ in the schematic here (dm3 but the dm2 VRMs are essentially cloned) I'm not sure the offsets in bios do anything to affect these voltages unfortunately as the outputs appear fixed (except for vcore) and vcore/uncore are not seperately adjusted. I could be incorrect on this but it may be worth investigating 🙂 https://oem.whyopencomputing.ch/Computers/Service Manuals/2023.11.22_P775DM3_Service_manual.pdf

Life has been very busy so I haven't had much chance to work on this laptop for a long while until recently. Todays plans are to modify the current limit through PR27 which sets the OCP (144A on the DM3, 180A on the tm1g despite the same VRM configuration) changing from 30k - 38.3k there are 2 other resistors which require changing here , r177 and r162 in line with the p775tm1g schematic, I misunderstood their function before and there's a bit more going on than I first thought, the data sheet for the ncp81248 voltage regulator (close to the one in this machine) has the proper calculations for the resistor values on page 19* While the laptop is in pieces I am also converting to the modified A51M fans from Taobao, they require a PWM signal and unfortunately I did not buy the converter offered by the seller at the time so I must make my own, I am bypassing the onboard NCT3941S linear DC fan controller which takes a simple 0-3v input signal from the EC and outputs x4 the voltage to the normal fans, unfortunately the EC is not using PWM in this case which would have made my job easier! I will be using some small MCU to convert the 3v to a PWM signal to send to the fans. For now all I will be doing is attaching a breakout cable so I can tinker more with the fans externally without needing to run jumper wires to the board. More updates soon.

A strange question but what slot is your main NVME drive currently installed? I have trialed moving my drives around and putting my main drive in the slot under the main cover and not the cover for the subwoofer / SATA drives, this from some small testing seems to have improved the issue? very strange.

A small update on this project, I have pulled the laptop apart for some unrelated modifications to the fans and while it is apart I'm going to change the current limit resistor and hopefully not explode it! 😅 While I have it open I will also be modifying the Imax value through PR190 so throttlestop isn't necessary for running over 120A to the core. The changes are as follows: PR27 (OCP set) 30k -> 38.3k PR190 (IMAX) 95.3k -> 110k

Hello! this is a behaviour of the embedded controller causing the CPU to throttle when GPU load is applied, unfortunately this is seemingly only solvable with premamod EC firmware but that is practically impossible to find:( throttlestop will do fine as it continuously overrides the register change the EC makes

this sounds similar in issue to what I experienced, I believe there is an issue with one of the drivers that gets automatically pulled and it's congestion on ambush, if you put your system under load and hold a key then release do you continue to see keystrokes for a short time after releasing?

after more testing I have realized the bios change does not fix the issue 😞 I will be doing more testing with different drivers to try and diagnose it