Originally Posted by TwoCables
I know how this will sound, but everything you need to know about this really is in your motherboard's manual. Not only that, but the PCB itself is usually labeled. So, look closely.
Beyond that, it's impossible to help without knowing which motherboard you have.
Ditto. Motherboard come in various different sizes and configurations. Even giving us a hint like AMD or Intel isn't going to help. You can take 10 different Intel or AMD motherboards and lay them side by side and all of them will be different. However, it's not all that difficult if you think it through....
I like to start with the fans. Depending on how many you have and if you are a big stickler of cable management, this could take a minute or two. Motherboards vary too much in fan header placement to give you a set place to look. But, they are 3 and 4 pin inputs located around the board in different locations.
Next up are the ATX (really big rectangular connector) and 4,6, or 8 pin power supplies for the motherboard.
USB Headers and Front Panel:
Next up, work on your USB headers. The plugs for these are generally along the bottom of the motherboard. Also generally with the USB headers are the front panel headers (power switch, power LED, hard drive activity LED, etc.).
The front panel header is most often in the bottom right corner of hte motherboard -- it's pretty easy to tell as it features several different colored pin placements that correspond to the different colored wires coming from front panel.
Finally, start working on your hard drives/dvd drives/and other SATA devices. Motherboards vary from 4-10 SATA ports and are usually midway up the board on the right side. They're numbered SATA_0 through however many SATA ports you have. REmember, because it starts counting at 0, if you have 8 ports you'll only go up to SATA_7
After all of that, you can install your PCI devices and hook up their power (if needed) as well.
It's really not all that difficult. Your motherboard manual is a big help though. Combined with a somewhat systematic approach like above, you should be good to go.