T25 can take ANY T470 motherboard and 64GB RAM

[RealBlackStuff]

Just found this on Reddit: I made a pretty cool discovery regarding the T25 (Anniversary Edition) and the T470! (sort of long)

[dr_st]

I imagine it is the same fellow posting here under the name DaddyLongLegs, as I find it very hard to believe that two different people with this rare model can be so unlucky to have the motherboard die on them 4 times in 3 years... A lot of the story is also similar.

Anyways, we already knew that the T470 and TP25 BIOS is the same, and we knew that you can mix and match many parts including motherboards between TP25 and T470/T480 (else the T480 mods would not be possible). What I learn from this story is that the T470 motherboard is a drop-in, and the BIOS automatically detects the correct keyboard. This is something I was not sure about until I read this, as theoretically the logic that determines whether it is a 6-row or 7-row could have been in some embedded chip on the motherboard. Glad to know it is not the case (assuming I understood everything correctly).

[TPFanatic]

Nice that the T470 and other 2-RAM slot 7th gens can use 64 GB RAM.
6th gen like T460 can also do 64 GB.

But the 4-RAM slot models like P50, P70, P51, P71 are still limited to 64 GB RAM. Even if you use 32 GB sticks to physically install >64 GB RAM, the BIOS will only report 64 GB, and the OS may acknowledge the increased RAM but reports only 64 GB usable. Oh well.

https://forums.lenovo.com/t5/ThinkPad-P ... -p/4390604

https://old.reddit.com/r/thinkpad/comme ... _possible/

[mikemex]

But the 4-RAM slot models like P50, P70, P51, P71 are still limited to 64 GB RAM. Even if you use 32 GB sticks to physically install >64 GB RAM, the BIOS will only report 64 GB, and the OS may acknowledge the increased RAM but reports only 64 GB usable. Oh well.

It's easy to read the EEPROM, do some math and come up with the amount of memory installed. Having the ability to access different memory configurations is a different thing. Some memory controllers simply aren't wired flexibly enough (probably for energy saving reasons) so they "inexplicably" can't handle memory profiles that are possible, but were unavailable at the time of design. The Montevina series is a good example, as you can't install 8GB unless you use 8 chips per side 4GB DIMMs (4GB with 4 chips per side do not work). Which is a shame because (usually) the less amount of chips, the more advanced the lithography process.

Despite all other improvements, memory is still a parallel interface. And parallel interfaces are notorious for having difficulties adapting to different profiles. That's why they were experimenting with serial memory years ago, but it didn't caught on. I'm sure they are going to try again at some point.

PCI Express is a good example of how serial interfaces tend to replace parallel ones. And on top of that we're going to see hardware level networking (packet model).