Open Terminal: Applictions --> Utilities --> Terminal
Get root permission: sudo -s
Open property file: vi /Library/Perferences/SystemConfiguration/com.apple.Boot.plist
Goto insert mode : type "i"
Add context: <key>Graphics Mode</key>
<string>1024*900*32@60</string>
Goto command mode: press "Esc"
Save file: type":w"
Quit vi: type ":q"