Best answer: Yes, you can upgrade the pre-installed 4GB of DDR4 RAM inside the ASUSTOR AS5304T with an additional module to bring the total up to 8GB.
Upgrading the RAM
It’s possible to upgrade the RAM inside the ASUSTOR AS5304T easily by removing all four drive bays, exposing the RAM module slots on the left-hand side. While one can purchase an official RAM module from ASUSTOR, which would match the pre-installed module, this would set you back double the cost of an 8GB RAM kit from Corsair.
The better route would be to extract the pre-installed 4GB module and store it away somewhere safe. Install our recommended 8GB kit from Corsair, and not only are you doubling the capacity of the NAS and saving money in the process, but you’re also using slightly faster memory. A win all round.
Overpriced, but officially supported
If you prefer to use the only RAM specified and marketed by ASUSTOR to ensure compatibility, then there’s no other option than the official ASUSTOR 4GB upgrade module. The only downside is the price.