Okay. Let's start with the motherboard, and power cables coming from the Power Supply;
A) The eMachines T3642 Desktop PC uses a
Foxconn (WinFast) MCP61SM2MA motherboard,
(The Form Factor is Micro-ATX. (uATX)
It uses an AM2 processor socket )
Power unplugged from computer, AND Anti-Static Precautions FOLLOWED.
Your body carries Static electricity. Static WILL fry out (Short Circuit) the delicate hardware components inside a computer.
Computer on a table, computer unplugged from power, computer case open.
TOUCH an unpainted surface, of the metal frame of the open computer case.
This action will relieve your body of Static.
IF, you leave your computer in the middle of working on it, be SURE to Touch the metal frame again upon your return ]
Click on the link in 1) above. This shows the bare motherboard with no hardware components attached, or power cables from the Power Supply, or any other cables attached. (Cables = Wires)
Scroll down to the photo of the motherboard.
Look at the Yellow long, Ram Memory slots, that are vertical. (2 each)
To the right of them.
A1) The whitish connector that has two columns of 12 socket holes, is the 24-pin ATX main power cable connector.
This is a general example of a 24-pin ATX power cable, and it's respective connector on the motherboard,
(NOTE* Color of power cable connector, and connector on motherboard, Does Not matter),http://www.playtool.com/pages/psuconnectors/connectors.html#atxmain24
View the photo to the far right. Note the Lock on the power cable's connector, and the Lock Tab on the motherboard's connector.
The hooked end of the Lock, MUST be hooked over the tab, to ensure the power cable is plugged in tightly, and correctly.
A2) Look at link 1) again.
Look at the Top/Left side of the motherboard. See that whitish square connector with 4 socket holes?
That is a 4-pin ATX +12 Volt power connector.
A 4-pin ATX +12 Volt power cable plugs into it. This power cable's connector also has a Lock,http://www.playtool.com/pages/psuconnectors/connectors.html#atx12v4
A3) The Harddrive is a SATA unit. It has a SATA power cable that plugs into it, and a SATA data cable that plugs into it.
The SATA headers (Connectors) on the motherboard, are seen in link 1), and are to the bottom/right. There are 2.
They are Blue in color, and are above the green headers.
This is where the SATA data cable of the harddrive plugs in.
Straight connector. Elbow connector plugs into the back of the Harddrive.
The SATA data cable connector has 7 pins.
The SATA power cable has 15 pins. It is the longer connector,http://www.playtool.com/pages/psuconnectors/connectors.html#sata
Which SATA header on the motherboard, should the SATA harddrive's data cable plug into?
SATA1. The top header. (Connector)
The beauty of SATA however, is that you can connect in EITHER connector, and BIOS will find the harddrive.
Note the L shape on the inside of the power cable connector, and the data cable connector. There is a matching L shape for the connectors on the motherboard, and the back of the Harddrive. Line these up when installing the cables.
A4) The optical drive/s (CD/DVD drive) may be SATA, but I'm betting the optical drive/s are IDE. (PATA)
The optical drive/s will use a flat ribbon cable, for a data cable, and it plugs into the long Blue connector, seen in link 1), to the bottom right of the whitish 24-pin ATX main power cable connector.
On the flat ribbon cable is a faint red stripe. It is on one side, and the side that has number 1 pin.
To line the cable up correctly when installing To the motherboard, use the cutout in the connector. The flat ribbon cable's connector, should have a Lug on the outside, which lines up with the cutout.
IF NOT, the faint red stripe side of the cable, goes down towards the bottom of the motherboard.
Looking at the photo, and the IDE (PATA) connector on the motherboard, number 1 pin is at the Bottom/Right corner, of the motherboard connector.
The flat ribbon cable's Lug, also lines up with a cutout in the connector, at the back of the optical drive.
IF the cutout is not present at the back of the optical drive, or there isn't a Lug on the connector, the faint red stripe goes to the RIGHT side of the optical drive.
(Doesn't matter if the flat ribbon cable is twisted. The faint red stripe ALWAYS goes toward the power cable connection, on a drive.
Harddrive, or optical drive.
Number 1 pin is the pin closest to the power cable connection on the drive.
More in a Comment.