SATA cables have only connectors on the end of the cable, one connects to the motherboard and the other to the drive and they usually are a half an inch 12.5 mm wide and are "L" shaped. IDE cables have a connector that attaches to the motherboard and have two connectors for two drives and unless they are round IDE about 2.5 inches wide and are straight across.
What is the model number of your motherboard and or computer. If you have SATA connectors on your motherboard there may be more that two, so you may not have to disconnect your DVD drive and have addition SATA power connectors. The IDE drives also have four pin MOLEX power connectors. SATA drives have SATA power connectors, which are "L" shaped and about 7/8" wide. Some older SATA drives had both MOLEX and SATA power connectors, but the MOLEX connectors have been dropped from newer drives. As Mimoso indicated you may have to change your boot order in the BIOS either way. Yiou may mot see the second HD in your OS, if you have Windows, you may have to go to disk management and format the new HD and assign it a drive letter.