Here are the specs for each computer:
T430
| Memory |
|---|
- PC3-12800 Non-Parity (NP) Double Data Rate Three (DDR3) Technology
- Two SO-DIMM Slots
- The use of 1600 MHz SO-DIMM memory is recommended for this system.
- System automatically clocks down for processors with 1333MHz DDR3 memory controller
- 2 GB, 4GB, or 8GB memory
- Supports up to 16GB maximum memory
- Intel Turbo Boost 2.0
Note: Only 64-bit operating systems support more than 3GB of system memory (RAM).
|
T420
| Memory |
|---|
- PC3-10600 Non-Parity (NP) Double Data Rate Three (DDR3) Technology
- Two SO-DIMM Slots
- The use of 1333 MHz SO DIMM memory is recommended for this system.
- 1 GB, 2GB, or 4GB memory
- Supports up to 8GB maximum memory
- 2GB, 4GB Intel Turbo Memory (selected models)
Note: Only 64-bit operating systems support more than 3GB of system memory (RAM).
|
It looks to me that it will depend on how the T430 arrived at 8 GB. If it was with a single DIMM then no, it won't work since the T420 can't use that capacity DIMM. Other than that, it will depend on what type of performance will be derived from putting a slower DIMM in the T430, as it is designed for the PC3-12800 spec with 1600 MHz ram. I don't know if it will be able to adjust to the slower spec DIMM.
