How come the i3-N305 can be run with 32GB of RAM when Intel's spec sheet says max 16GB?

[tibbe]

Intel spec sheets says the i3-N305 supports 16GB of RAM: Intel® Core™ i3-N305 Processor (6M Cache, up to 3.80 GHz) - Product Specifications | Intel

Yet I see lots of people using 32GB sticks and report that it "works" e.g. in https://forums.servethehome.com/index.php?threads/cwwk-topton-nxxx-quad-nic-router.39685/.

What's the story here? Does it really work?

- Can all the 32GB actually be used or is it just reported (e.g. by the BIOS) as being installed?
- If it all can be used, are there downsides from using >16GB, like slower memory access?

 

[Wasmachineman_NL]

Intels spec sheets are often wrong or outdated. Case in point: X58 being able to run 6x8GB.

 

[alaricljs]

Intel spec sheets are written at 1 point in time and only revised for dates, eg: eol.

At the time it was written higher density dimms were not available hence could not be validated and supported.

As long as the higher density dimm are electrically compatible you should be good to go. This means things like voltage, rank, and so forth

 

[tibbe]

Are there no limitations in how much memory the CPU can address?

 

[Wasmachineman_NL]

Are there no limitations in how much memory the CPU can address?

Unless you go RDIMM anything goes. This ain't the Pentium III era.

 

[JanR]

Are there no limitations in how much memory the CPU can address?

Obviously, the limit is given by the number of address lines. This can be seen by "lscpu" or "cat /proc/cpuinfo" running Linux. The interesting item is "physical address size".

Example 1:

Xeon X3470 (Lynnfield generation): 36 bits physical which means 64 GB. For UDIMM, Intel specified at time of release 16 GB maximum memory (DDR3, 4x4 GB). However, I run my X3470 with 4x8 GB (32 overall) since some years with no problem. 64 GB would only be possible using DDR3 RDIMM.

Example 2:

Core i9 13900K reports 46 bits physical. This translates to 64 TB which is far beyond the capabilities of todays memory. Therefore, Intel specifies 192 GB (4 x 48). However, since 4 x 64 GB would need exactly the same number of address bits (38) this is most likely also possible once 64 GB DDR5 modules are available.

 

[RolloZ170]

Obviously, the limit is given by the number of address lines. This can be seen by "lscpu" or "cat /proc/cpuinfo" running Linux. The interesting item is "physical address size".

check first how much address line come out of the memory controller to the DIMM slot.
this was the limit in early gens(rank size support)
remember 8GB DDR3 modules "for AMD only"