PHVM_BR

From the 12th generation onwards Intel removed the possibility of undervolt from H series CPUs. For laptops only HK and HX CPUs can have their voltage adjusted. Try PTM 7950, in addition to excellent performance it should correct small imperfections in the heatsink contact.

What is the TGP that the Nvidia control panel reports? Performance will depend on TGP. I believe that on the Precision 3581 it should be limited to ~50W.

What exactly does this? I unlocked it out of curiosity and my i9-9980HK clocks were stuck at 800MHz. To unlock undervolt and increase ratios this is not necessary, what does it do?

BIOS defaults return the configuration of the installed BIOS. If the installed version is anything above 1.7.0 this will block the undervolt. Factory Defaults returns the original factory BIOS configuration. If the original BIOS is 1.7.0 or lower this option will unlock the undervolt. If it is 1.8.2 or higher, this option will block undervolt if it is unlocked.

It's not a 5540, but I tried charging via USB-C on the Precision 7540 with a 100W GaN charger from Ugreen and it's not supported. I thought it was a problem with both USB-C ports, but I tried charging via the USB-C port on the Dell P2723QE monitor (USB-C Hub 90W) and it worked perfectly. It's probably some deliberate blocking by Dell only being compatible with their devices.

Have you tried restoring factory settings in BIOS? If your laptop left the factory with BIOS 1.7 or lower this is enough to restore the possibility of undervolt. Otherwise, the option is to edit the variables (very simple).

RTX 2000 Ada = RTX 4060

I purchased a 240W Alienware SFF (GaN) power adapter and it works great on the Precision 7540. As before with the original 180W power adapter at full CPU + GPU cross-load, the i9-9980HK remained at ~60W and the RTX 4000 at ~90W but now there is no more battery drain. The system works by consuming ~150W from the CPU and GPU simultaneously, around ~180/190W in total, without discharging and without thermal throttling. Impressive! I'm very pleased with the new investment (i9 / RTX 4000 / 240W adapter).

The problem is definitely the lack of battery. I did the test without battery running AIDA64 CPU test + Heaven. With BD PROCHOT the CPU worked inconsistently, varying between ~15 and 30W while the GPU also fluctuated, unable to maintain a constant ~90W. While the tests were running, the BD PRO alert flashed red constantly in the ThrottleStop main window. By unchecking BD PROCHOT, the GPU started to work apparently normally, while the CPU continued to oscillate strongly, but with higher power levels, between ~15 and 60W, mainly between ~20 and 50W. This time the POWER alert flashed red constantly.

Tomorrow I'll try to test and post the results here. See the screenshot of the ~14 minute test I did simultaneously using the AIDA64 CPU Stress + Heaven still with i7-9750H / RTX 4000 (90W VBIOS) / original Dell thermal paste from the new heatsink / no undervolt:

I seriously believe it's the lack of battery. Many systems, especially with dGPU, limit heavy usage when there is no battery connected. In ultra performance, your laptop should maintain at least 45W on the CPU simultaneously with the GPU. In fact, I believe that the default behavior of this machine is for the CPU power to fluctuate between 60 and 45W (depending on temperatures) while the GPU consumes its 80W. My original system had an i7-9750H and Quadro T2000 and the behavior at full load CPU + GPU was the i7 varying between 60 and 75W while the GPU maintained 60W (its maximum TGP). In the case of RTX 3000 or higher, this CPU limit is lowered as the GPU consumes more (80W).

I believe we discovered the culprit: it's the absence of the battery!

Are you running these tests with the original charger connected?

45W for the CPU is very little for this machine. You should be able to sustain 75W at ultra performance all day... Yes, I never had any limitations like that even with thermal paste and original pads (the thermal pads I use are the original ones from the new heatsink assembly I bought for the RTX 4000).

Does this behavior occur when in ultra performance mode in Power Manager? My 7540 can constantly maintain 60W (~90/92°C) on the CPU (i9-9980HK) if I force it by blocking the power limit with Throttlestop in parallel with 90W (~77/79°C) on the GPU (RTX 4000), but at this level the battery will be drained heavily even with the 180W charger. If I limit the CPU to 50W the battery drain does not occur and the temperatures decrease. I believe you need new thermal paste for the CPU/GPU and probably new thermal pads for the VRMs as well. If your system came with BIOS 1.7.0 or lower, you can update to any version and your undervolt will remain unlocked. If the original BIOS is 1.8.2 or higher and you can undervolt it will remain unlocked even if you update to the latest version, you just cannot restore factory defaults or BIOS defaults.