Fully disable/shut down GPU as if not connected: possible?

My goal is to reduce the needed power as much as possible, in sum it should be under 30-40W. For this, I need to also disable my GPU in a way it consumes 0W or nearly 0W. I will use my CPU instead. I am fine with changing this per boot. This is not regarding a laptop but regarding a self-build PC with an AMD processor, so there seems no prime-select available as far as I am concerned.

Currently, I have it connected and running for my main display and processing. This consumes around 20W when using the browser or similar daily use apps.

What I have already tried:

• Put a 1 into the "remove" file in the dev device (if I remember right) (no notable effect)

• Restrict or disabled it via TLP (only Hz etc. seems "possible" but had no notable effect)

• Restrict it via Nvidia Driver (able to restrict to lowest Hz but nearly no effect = 15-20W consumed)

• Use software to switch between GPU and internal GPU (would disable the GPU) but this errored and lead to system crashes

• Disable all NVidia Drivers at boot (nearly no effect, also tested together with dev/remove)

• Switch the primary output in the motherboards settings to the internal GPU (no effect with normal usage as described above)

• Remove it physically (reaches the 30-40W I want, but damages the GPU's pins and is hard to do from outside the case)

I also already thought about a switch I could implement into the extension cable, but I heard, the GPU works at such high speeds that if the cable length would only change a few mm it could lead to failures.

The Nvidia driver does a lot of this already.

If I turn my monitor off, and watch nvidia-smi dmon over SSH, the clock speeds drop right off. I've cherry picked three readings, one from before turning off my screen, one immediately after turning it off, and the wake-up reading (full speed for a couple of seconds)

# gpu    pwr  gtemp  mtemp     sm    mem    enc    dec    jpg    ofa   mclk   pclk 
# Idx      W      C      C      %      %      %      %      %      %    MHz    MHz 
    0     44     41      -      2      2      0      0      0      0    810    615 
    0     25     40      -      0      0      0      0      0      0    405    225 
    0     42     42      -      8      1      0      0      0      0  13801   2332 

No, it's not physically severing the PCIe lanes, or unplugging the 12VHPWR cable, but 25W is a lot better than active idle. This is a 5070 Ti, a relatively high power card so the difference I'm seeing might be greater than lower power cards. There's going to be a power saving floor.

You can soft-turn-off PCI slots. And I've seen other people talk about unbinding drivers too, but the card is still going to be there, plugged in with all its VRMs doing VRMmy things, capacitors capacitating, etc, etc. It's always going to draw some power.

If you absolutely need zero power out of it, you're probably going to need to look to an external PCIe dock that you can pull the power on after it's soft-disconnected. These are many and varied (occulink, thunderbolt, etc) but often come at with a performance penalty. Higher power when they're being used too.

Physically switching DC is not always simple. This card can pull 330W worst-case. If you switch that with a flimsy little switch at full current, it could arc out, corrode the contacts and start a fire. Thanks to cars and boats, there's a lot of well-rated 12VDC switches at the 30-50A range.

Still not sure I'd recommend it.