Dell Studio 1558 (Early 2010) - Manual (Page 321)

Ports
321
VGA Port
Video Graphics Array (VGA) port supports the basic graphic hardware before
a device-specific driver is loaded into the computer.
Pin Signal Pin Signal
1 RED Video 9 DDC 5V+
2 GREEN Video 10 SYNC GND
3 BLUE Video 11 MONITOR_DETECT–
4 NC 12 DDC_DATA (SDA)
5 GND 13 Horizontal SYNC
6 RED Video GND 14 Vertical SYNC
7 GREEN Video GND 15 DDC_CLK (SCL)
8 BLUE Video GND