Some interesting news:
I received a test console (DIA-002 with 40nm RSX and CXR713F120A Syscon) from @
vyktormvmpay25 
And that did some extreme speed up to the 40nm RSX Syscon patches development.
First I tried to copy the official Sony procedure, for that I flashed the 304GB (v1.5.1k2) firmware to the Syscon and performed the following patches to the original (DIA-002) EEPROM:
Code:
Fix thermal config unk: w 348B 8B
w 34AF 8B
Change RSX version to 40nm: w 3912 30
Write new training data: w 3F62 EF 87 F9 19
w 3F69 07 F9 1D
w 3F6F 1F F9 0D
w 3F74 EF 0F F9 0D
w 3FA2 03 61 82 80 01 91
(the thermal config fix isn't mandatory)
And it worked!
That's the first "official" 40nm swap that wasn't done by Sony.
But of course that's not really surprising since we just copy what Sony did.
After that test I flashed the 302GB (v1.4.4k2) firmware to Syson, that's the DIA-002 standard Syscon firmware.
I did apply many patches to that firmware to debug the RSX FlexIO training and discovered something very interesting! Even though the 90nm/65nm/40nm RSX need different FlexIO training data/algorithm you can just use the 90nm/65nm data/algorithm to train a 40nm chip and it'll work. RSX will complain a lot to Syscon but Syscon can ignore that.
To further test that I removed all my custom patches from the firmware, so now it's a stock 302GB Syscon.
By applying these patches to the EEPROM:
Code:
w 3242 03 61 82 80 01 91
w 3254 21 EC
a stock 302GB Syscon will train the 40nm RSX and the console will boot without any error.
And it doesn't matter wether 0x3912 is set to 0x11 for 90nm or 0x21 for 65nm. So you can train a 40nm RSX with the 90nm or 65nm data as long as you applied these patches to the EEPROM.
Just one note: If
w 3254 21 EC doesn't work, use
w 3254 21 EB since there're
two different 40nm chip variants.
I also did test that on the 203GB (v1.2.3k1) and 301GB (v1.3.3k1) Syscon firmwares and it works too!
(I needed to patch these firmwares in order to work on the DIA-002 but I didn't touch anything RSX related).
That means the same patches work on SEM-001 and DIA-001 (and of course DEB-001).
I can't perform the final test since I have no COK board with a 40nm RSX, but since the other chips can train a 40nm RSX with the 90nm training data, the same EEPROM patches should do the job on the 201GB/202GB Syscon. Maybe someone can test that
.
In summary (TLDR): A 203GB/301GB/302GB Syscon supports 40nm RSX after applying two EEPROM patches. 201GB/202GB haven't been tested yet but should in theory work since it's the same code.
A little extra: If you plan on replacing the 90nm RSX with a 65nm one, try these patches:
Code:
w 3242 03 A2 03 B0 07 71
w 3254 21 E8
Edit (NOT TESTED):
1) For SW/2 Syscons use offset 0x182 instead of 0x3242 and 0x194 instead of 0x3254
2) For SW3 Syscons use offset 0x212 instead of 0x3242 and 0x224 instead of 0x3254
3) For the 28nm RSX replace the second command with
w 3254 21 EE
