https://forums.lenovo.com/t5/Lenovo-Idea…6GB/m-p/4221948
In this thread me and several other users have the identical problem. Lenovo has intentionally crippled an upgrade path by locking Optane support to the 16GB module. 32, 58, 64 and 118GB modules cannot be used to accelerate the SATA drive.
This is not a natural compatibility issue, Lenovo has done something to restrict access to all but the 16GB module.
https://pcsupport.lenovo.com/us/en/produ…15ikb/downloads
I have moved onto another laptop already (Vivobook pro) so I don’t actually need a modified BIOS. I am just curious about this type of restriction and how they lock out hardware that otherwise would be completely compatible.
@nosirrahx - link me to an example BIOS and I will see if it’s just a hidden setting.
Since you used to have a system with this issue, how did you find out about the restriction, was there some notice given in the BIOS or at post, did the item work but only 16GB of it? Was there a BIOS setting where you might be able to choose the GB amount used?
* Edit - I checked the BIOS you linked, and nothing relating to this in settings, even hidden, except for to enable/disable Optane.
I looked at every setting that had memory in it’s name, every setting that had Optane (only 1), and looked through all the Chipset, PCH, SA, and all the SATA/RST and PCIE Settings. And I also generally browsed through all the settings visible and hidden, nothing jumped out at me
If you think I missed a section, or have a specific name/term from the BIOS you think I should look for, let me know. I initially looked for 16GB/16384MB as a setting choice in the options, none found, so it’s not a setting limited to that as an option with others hidden
I can give you a text file of all the settings if you want to dig through it and see if you can find something?
ECC memory support is enabled, for anyone looking later 
I bought the system with the intention of upgrading directly to a 32GB Optane module.
No matter what I did I was unable to enable RST with Optane support in BIOS. When I entered the info screen there was no drive listed.
Going back to the 16GB module the RST info screen in BIOS showed the drive.
I pulled it back out and tried every single Optane module there is (32, 58, 64 and 118). All of them are invisible to RST in BIOS.
In windows both RST and Optane software can see the 16GB module but the 32, 58, 64 and 118GB modules are listed as simple NVMe SSDs with no Optane support.
When questioned about this Lenovo support said that only the 16GB module is supported.
When questioned Intel reported that if there is a restriction, it is intentional and to contact Lenovo support.
@nosirrahx - see my edit above, I edited in a lot while you replied (I think, can’t remember how much of that was my initial reply )
By Default Optane via RST is enabled, and has no other restrictions or settings with it, see below for actual setting
One Of: System Acceleration with Intel(R) Optane™ Memory, VarStoreInfo (VarOffset/VarName): 0x660, VarStore: 0x5, QuestionId: 0x3E4, Size: 1, Min: 0x0, Max 0x1, Step: 0x0 {05 91 CE 0D CF 0D E4 03 05 00 60 06 10 10 00 01 00}
One Of Option: Disabled, Value (8 bit): 0x0 {09 07 54 00 00 00 00}
One Of Option: Enabled, Value (8 bit): 0x1 (default) {09 07 53 00 30 00 01} << Default applied setting
They may be using some kind of whitelist? Or whatever controls that is not part of the BIOS setup/settings section, which I was looking through
Whitelist was my guess. I will dig up the IDs for the 16GB module, perhaps they show up somewhere. If they do its probably an easy fix to simply substitute in the 32GB ID.
Yes, if you can find ID’s, maybe we can find the whitelist that way. It’s too bad there is no error given, that’s usually how to find the wifi whitelists.