R40 does not use the DDR333 capabilities of the B1 stepping variant of the 82855PM northbridge
Apparently, some late Pentium M-based R40 models came with a B1 stepping variant of the 82855PM northbridge. The FRU of this motherboard appears to be 93P3580, which is a Pentium M-based R40 motherboard with the Mobility Radeon 7500, IEEE 1394a-2000 4-pin port, and with the IBM Embedded Security Subsystem 2.0 chip.
The strange thing about it, is that CPU-Z reports the stepping as an A3. Even with the faster DDR333 modules, they will somehow downclock back to DDR266 speeds, can anyone confirm that this is also happening to a R40 that is with the B1 stepping variant of the 82855PM northbridge? And before I do forget some additional details, the motherboard revision is 0.9. --Bugmenot2 (talk) 17:35, 9 November 2018 (CET)