HP LaserJet Pro 400 color Printer M451 series - Manual (Page 145)

Install memory DIMMs
This product comes with 128-megabyte (MB) random-access memory installed. You can install an
additional 256-megabyte of memory for the product by adding a dual inline memory module (DIMM).
You can also install a font DIMM to allow the product to print characters (for example, Chinese
language or the Cyrillic alphabet characters).
CAUTION: Static electricity can damage electronic parts. When handling electronic parts, either
wear an antistatic wrist strap, or frequently touch the surface of the antistatic package and then touch
bare metal on the product.
Install memory DIMMs
1. Turn the product off, and then disconnect all power and interface cables.
2. On the right side of the product, open the DIMM access door.
3. Remove the DIMM access door.
ENWW Install memory DIMMs 127