Dell C521 specifications Drives, Connectors, Controls and Lights

card size	low profile
connector size	124 pins
connector data width	32 bits
(maximum)
PCI Express:
connectors	one x1 and one x16
power	10 W (x1) and 25 W (x16) maximum
connector size	36 pins (x1) and 164 pins (x16)
connector data width (maximum)	one PCI Express lane (x1) and 16 PCI Express lanes
	(x16)
Drives
Externally accessible	one 3.5-inch drive
	one 5.25-inch drive bay
Available devices	SATA hard drive, CD drive, DVD drive, DVD +/- RW
	drive, and CD-RW/DVD Combo drive
Internally accessible	one bay for a 1-inch-high hard drive
Connectors
External connectors:
Video	15-hole VGA connector
Network adapter	RJ45 connector
USB	two front-panel and four back-panel USB 2.0–
	compliant connectors
Audio	six connectors for line-in and line-out; two front-panel
	connectors for headphones and microphone
System board connectors:
SATA	two 7-pin connectors
Floppy drive	34-pin connector
Fan	5-pin connector
PCI 2.3	124-pin connector
PCIe-x1	36-pin connector
PCIe-x16	164-pin connector
Internal USB	10-pin connector (supports two USB ports)
Speaker	6-pin connector
Memory modules	four 240-pin connectors
Power 12V	4-pin connector
Power	24-pin connector
Battery	2-pin socket
Controls and Lights
Power control	push button
Power light	green light — Blinking green indicates a sleep mode;
	solid green indicates a power-on state.
	amber light — Blinking amber indicates a problem
	with an installed device; solid amber indicates an
	internal power problem (see System Lights).
Hard-drive access light	green
LAN activity light (front panel)	solid green light indicates network connection
Link integrity light (on integrated network adapter)	green light for 10-Mb operation; orange light for 100-
	Mb operation
Network activity light (on integrated network	yellow blinking light
adapter)
Diagnostic lights	Four lights on the front panel. See Diagnostic Lights.
Standby power light	AUX_PWR on the system board