Creality has been swapping CPUs on the V4 boards from 512K part numbers to 256K part numbers. These chips need different firmware builds to safely operate. Currently, the following board versions have been identified to have been affected by this part swap.
There is no way to know what CPU you have without looking at the CPU itself or if you purchased a board from us it will be specified what CPU version you are purchasing as we open and check every box before we stock them. We also will never sell the boards with the clone CPUs mentioned below.
There are also some clone/knockoff CPUs that say "GD32" in the part number, these also follow the 256/512K RCT6/RET6 part numbers for the memory size.
If your CPU says RCT6 on the line after STM32F103 then it is a 256K part.
If your CPU says RET6 on the line after STM32F103 then it is a 512K part.
There may be other boards that use the STM32F1 series CPUs but this is the confirmed list we have at the time of writing this article.
RCT6 256K CPU
RET6 512K CPU
