ASUS RTX 3060 Ti Dual Mini - starts but no video

[speaktorob]

I've already had a little help at r/GPUrepair to get me here. (kudos /u/khoavd83 ✊)

At this point I'm trying to figure out if the GPU is a dead duck or not, but I don't have a thermal camera to perform the proper test. I tried the iso alcohol evaporation technique but it was inconclusive. Anything else I can try?

The history of the card:

Bought second hand, cleaned it up. Tried to make a fan mod with some noctua A9x14's. Got the wiring right -- at first -- but had problems getting the fans to fire up. When probing the fan header for voltages, I shorted something in the header. Also relevant: at one point I swapped the PWM and Tach wires to see if I'd got them the wrong way around. (I know, I know).

Relevant resistances:

12V = 8.9kΩ
5V = 225kΩ
3.3V = 31kΩ
1.8V = 11Ω (uh oh)
MEM = 32Ω
PEX_VDD = 50Ω
GPU = 0.2Ω, GPU to 12V rail = 18kΩ

Story so far:

The header is a dual fan header with shared live and ground pins and two each of PWM and tach pins. Tach 1 shows only 60 ohms to ground (similar to the PEX rail). Tach 2 shows over 1k ohms. From reading resistances on other fan headers, it seems like the 60 ohms pin is the anomaly?

I already found two 0 ohm resistors that showed 150 ohms that connected the 12V rail to the 12V pin, which I've desoldered (replacements inbound), but I doubt they are the root cause.

[speaktorob]

Alright, so this is getting weirder.

I can measure 60-65 ohms on the 1.8V rail, or I can measure 10 ohms, depending where I measure from.

I've desoldered the inductance coil for the 1.8V rail to better figure out where the low resistance is coming from. When I measure from the solder pad going backwards to the VCC - nada, megaohms, all good. Measuring from the other solder pad going to the rest of the rail, its like 10 ohms to ground here. Same goes for the 6 capacitors in parallel next door that are presumably for frequency attenuation or whatever - they are 10 ohms to ground.

If I measure from anywhere else directly on the rail, its 60-65 ohms.

What gives?

[speaktorob]

Anyone have an idea what to try next?

* I desoldered the 1.8V coil and confirmed the low resistance is in the rail, not the voltage controller
* The resistance is 10 ohms at the coil, but 65 ohms elsewhere around the board
* I've examined the board but can't find any obviously dead components
* I can't really inject voltage because I still have 10 ohms