@redxps630​ 

Thank you for the info.

The 12V and GND were not hard to figure out, you just confirm what I had found.
The question were the PINs 1, 4, 6 and 9, which you just gave me 1- PS_ON and 9-PS_OK.

I've got a refurbished Dell Precision 7865 MB and a Threadripper Pro 5955WX CPU at eBay, so I was trying to figure out how to make that work.

I have some standard ATX PSU here and I am going to make a adapter.

Many thanks.

@redxps630​ 

Sure, I will keep researching, and if I figure out something I will let you know.

@redxps630​ 

https://www.reddit.com/r/Alienware/comments/1468q26/dissecting_the_1350w_r15_psu_into_a_r13/

https://www.reddit.com/r/Alienware/comments/128ivl7/dissecting_the_r13_psu_750w_1000w_r15_1350w/

Based on those two posts I figured this out:

What do you think?

Regards.

@redxps630​ 

I think we can just ignore the I2C signals, I don't believe the PSU status (the I2C function) would avoid the MB start up.

In any case, I am looking for circuit with I2C communication.

Aliexpress has some like this one:

https://www.aliexpress.com/item/1005007457610338.html?spm=a2g0o.productlist.main.25.55874853n244h6&algo_pvid=f0427a61-2f0a-40a4-b968-dafbe737f170&algo_exp_id=f0427a61-2f0a-40a4-b968-dafbe737f170-12&pdp_npi=4%40dis%21USD%211.75%211.68%21%21%211.75%211.68%21%402101fb0b17244516765928309e4ecc%2112000040834958648%21sea%21BR%21106423096%21X&curPageLogUid=OohP2U7sLp60&utparam-url=scene%3Asearch%7Cquery_from%3A

This one has 3 channels:

https://www.aliexpress.com/item/1005006615865311.html?spm=a2g0o.productlist.main.9.55874853n244h6&algo_pvid=f0427a61-2f0a-40a4-b968-dafbe737f170&algo_exp_id=f0427a61-2f0a-40a4-b968-dafbe737f170-4&pdp_npi=4%40dis%21USD%211.79%211.72%21%21%211.79%211.72%21%402101fb0b17244516765928309e4ecc%2112000037831173022%21sea%21BR%21106423096%21X&curPageLogUid=IebDyVEbUqL9&utparam-url=scene%3Asearch%7Cquery_from%3A

I also found this 24 pin to 8 pin adapter for Dell Optiplex. which seems to have some sort of circuit, maybe a I2C circuit which we can adapt?

https://www.aliexpress.com/item/32890447301.html?spm=a2g0o.productlist.main.1.64421cadSyX3uo&algo_pvid=8cf7707d-2fd7-4b19-b95e-9240f0276beb&algo_exp_id=8cf7707d-2fd7-4b19-b95e-9240f0276beb-0&pdp_npi=4%40dis%21USD%213.50%213.35%21%21%213.50%213.35%21%402101c67a17244521688056581e6775%2165757072855%21sea%21BR%21106423096%21X&curPageLogUid=iZ6f2ulMgjwa&utparam-url=scene%3Asearch%7Cquery_from%3A

Regards.

jbmaciel.

this is the new Dell 12 pin proprietary socket used in Aurora R15/16.  pinout is only partially figured out and no known adapter exists from standard atx 24 pin.

Dell proprietary version of ATX12VO

you could use Dell proprietary 8 or 10 pin psu for XPS 8950 etc.  the 12 or 10 pin has additional 12V pins than the base 8 pin.

a Dell psu with 8 pin can power up the motherboard.  it is not required to plug in a 12 pin.  the additional 12V pins are for high power gpu needs.

for example the 8 pin can plug in 10 or 12 pin socket and power up motherboard

https://www.dell.com/community/en/conversations/xps-desktops/xps-8950-power-connector-pinout-diagram/647f99fcf4ccf8a8ded82803?page=2

The red and brown pin are what I can’t figure out. If you are successful pls let me know which will help other users

that is impressive.  looks like you cracked the Dell code.

what does 12C-CLK and 12C-DATA mean?

The Inter-Integrated Circuit (I2C) Protocol is designed to facilitate communication between multiple digital integrated circuits referred to as “peripherals” and one or more chips acting as “controllers”. It enables serial communication among numerous devices using only two wires.

I2C Master Slave communication

SDA (Serial Data line) — The master and slave devices send and receive data over this wire.

SCL (Serial Clock line) — The line that carries the clock signal.

Similar to other similar protocols, I2C operates as a serial communication protocol where data is transmitted bit by bit along the SDA line. It is synchronous, indicating that the bit output is synchronized through the SCL clock signal generated by the master. The master always controls the clock signal

not sure how to make a 24 pin adapter based on that.  how do we make the 12C cables?

I thought Gray is PWR_OK,

What is Red Alert?

the old Dell 8 pin in your last 24 to 8 pin adapter

https://www.dell.com/community/en/conversations/inspiron-desktops/dell-proprietary-old-8-pin-and-new-8-pin-different-pinout/647fa251f4ccf8a8de7cb807

Dell old 8 pin

Optiplex 3020/7020/9020/XE2 (and 3040/5040/7040)

Inspiron 3650, 3670, 3671 (and 3250)

Vostro 3650