Due local display via VGA/HDMI need share system memory, if you have no this function anymore would let all memory for NAS, please refer to following patch

******************For OS7 if need no the HDMI/VGA local display function******************
Please Unzip the ZIP file, then install "Atom_default.patch" via firmware upgrade interface & reboot to fix this issue.
[CONTROL PANEL->FIRMWARE SETTING] and then press [SELECT] button.
Download & unzip http://www.thecus.com/Downloads/beta/ATOM_RAM_4G.zip
(same patch file as OS5 X64)

******************Since FW OS5 X64 V2.04.1 please refer to following article******************
If need system support the memory over 4GB please update to latest V2.04.01.1 or above FW.
http://www.thecus.com/Downloads/beta/FW/64_V2.04.01.1_build7041_FW_N2800_N4510U_N4800_N5550_N7510.rom
http://www.thecus.com/Downloads/beta/FW/64_V2.04.01.1_build7041_FW_N2800_N4510U_N4800_N5550_N7510.txt

After firmware update & reboot, if ADMIN WEB UI->SYSTEM INFO->HARDWARE INFO show up to 3xxx MB only, please: 

1. Download & unzip http://www.thecus.com/Downloads/beta/ATOM_RAM_4G.zip
2. Unzip the ZIP file, then install "Atom_default.patch" via firmware upgrade interface & reboot to fix this issue.

******************Before FW V2.04.1 please refer to following article******************

How to make all memory for NAS, if installed 4GB memory or above for N2800/N4800/N5550/N7510/N4510U.

Since firmware V2.03.08 or above firmware limited the memory to 4GB (Thecus default 2GB on NAS) from Intel ATMO specification, and reserved 1GB for Local Display function, if don't need the Local Display function, you could upload the "Atom_default.patch" via firmware upgrade interface and reboot NAS, and you will see the 4GB memory from NAS HW info interface.

1. Please download from http://www.thecus.com/Downloads/beta/ATOM_RAM_4G.zip
2. Unzip file, and upload "Atom_default.patch" from firmware interface.
3. After reboot NAS and we will see the 4GB memory available from NAS HW info interface.

*Once you need the Local Display function, please upload the "Atom_4G.patch" make system back to 4GB as above steps again. Or upload same version firmware again either.
**After firmware upgrade would make system back to 4GB and reserved 1GB for Local Display function, you have upload the patch again.