PcBytes wrote:

Voltage regulator: tab gives infinite, right tab gives 4.6 Ohms, left gives infinite

Voltage regulator - what do you mean by that? I've thought it's usual MOSFET in this place.
Is right tab of it connected to LX1664 (pin 10 Ldrv "Linear regulator drive pin") ?
P.S. Schematic for LX1665 is slightly different from LX1664 (datasheet)

Measured, and got 1.02v on the pin, while the linear regulator (AMC7584-3.3ST)'s right tab gave me 2.60V.

PcBytes wrote:

Measured, and got 1.02v on the pin, while the linear regulator (AMC7584-3.3ST)'s right tab gave me 2.60V.

😕
AMC7584-3.3 have to give output voltage 3.3v I suppose.
I would recomend to draw schematic diagram of the VRM(s) and figure out their components purpose.
I don't have such mainboard in hand and your photos don't give me much about connections.

Yes, it's supposed to give 3.3v.

I have an idea but first, Roman555, tell me - will it work?

Checking out the PDF for the LX1664 I found out that the gate pin for the MOSFET I have would be grounded then fed back into pin13, BDRV.

Would wiring the GATE pin of the mosfet directly to pin13 work?

PcBytes wrote:

I have an idea but first, Roman555, tell me - will it work?

Checking out the PDF for the LX1664 I found out that the gate pin for the MOSFET I have would be grounded then fed back into pin13, BDRV.
Would wiring the GATE pin of the mosfet directly to pin13 work?

I just haven't understood what you're going to do. Maybe my poor English. Try to draw.
Ok, I'll try to answer.
The GATE shouldn't be grounded at all. But your previous measurings have proved it isn't: the only pin that is grounded is the SOURCE of the middle MOSFET.
BTW, you know, the diagram from the datasheet could be somehow changed by the manufacture of the mainboard. So I did recommend to draw the real schematic of the VRM.

PcBytes wrote:

Measured, and got 1.02v on the pin, while the linear regulator (AMC7584-3.3ST)'s right tab gave me 2.60V.

I've rolled back. Just want to clarify. I'm still not convinced about the regulator.
By this datasheet for AMC7584-X.X the right pin of the right component in package TO-263 should be connected right to the ground rail if it's really a low dropout regulator with fixed voltage output (AMC7584-X.X).
If it's a a low dropout regulator adjustable then the right pin should connected to a resistive divider.
But in case it's a MOSFET (as shown in datasheet for LX1664) the right pin should go to LX1664 (pin10 Ldrv).
So, please, could you say where the right pin of the right component is connected? (dirrections correspond to your photos)
It's pity I couldn't find in the Internet good photos of 5VDM to read names of these components.

Maybe this helps. There are 3 MOSFETs, one 60N03S and two NDB6030L.

Hmm... you might just found the problem - the AMC7584 wasn't suited for the application...

Will try swapping in a 60N03S equivalent(the other two I put on mine are HUF76137 - the only difference between your NDB6030L and my HUF76137 is that mine are 75A) and report back if it comes back to life.

quicknick wrote:

Maybe this helps. There are 3 MOSFETs, one 60N03S and two NDB6030L.

Definitely