This little bugger is the ATX12V or more commonly known as the P4 power connector. The name comes from the fact that it was devised to power some of the early Pentium 4 motherboards that simply required more juice. It looks similar to the 20 to 24 pin extension cable, but they are not compatible with one another, so you can’t insert the wrong one into the P4 power slot.

The two IDE drives we have installed into our PC will require power to work as well. Molex power connectors come into play here. A few years ago when nearly every storage device used a Molex connector it was quite common to run out of them, but today this is no longer the case. As you can see in the second picture we also connected the floppy drive. We used the floppy drive power connector, which can be found at the end of a Molex rail (it is the last connector on a Molex cable).

The SATA storage device uses a different power connector, although most still have the old Molex connector as well. You are advised to use a SATA power connector if possible. DO NOT try to connect both power connectors at the same time, as this is a surefire way to damage the device.

The graphics card we used for this guide doesn’t require additional power, as it gets all the necessary electricity from the PCI-E slot. If we went with a faster and more powerful card we would have probably needed to use the PCI-E power connector, seen in the picture. Using it is a matter of plugging it into the appropriate connector on the graphics card.

Finishing up

At this point we are mostly done. What remains is binding all the lose cables together so that they don’t interfere with the air flow in any way. Empty drive slots are a good place to squeeze some of the extra cables, as is the empty space next to them. This is also the time to connect the case fans if there are any installed. This can be done either via a Molex connector or by connecting the fans to the fan connectors on the motherboard (every motherboard has at least one such connector). The decision about which to use isn’t really yours to make, as you’ll have to go with whatever connector your case fans have (our front and back fans both use a Molex connector).

Before you seal the case you might want to try turning the PC on (keep your hands outside of the case at all times though) to see if there are any problems such as cables getting in the way of fans or cables that you might have forgotten to connect. Once you are sure everything works turn the PC off, disconnect it from the power source and put back all of the face plates. That’s it, you are done!

If you have trouble understanding any part of the guide, feel free to ask for help in our forums in this thread. The DH members will be more than happy to help you out with further hints and troubleshooting help – don’t worry, they don’t bite!

Special Thanks to Sapphire for supplying some of the hardware in the article today !