I have a 3.5" laptop hardrive and I want to connect it to my desktop. The motherboard has a spot for sata and I got the sata cord...My question is..Do I need to connect the power supply to the hard disc still or does sata take care of that and if not then what kind of adapter would I need to fix this problem? Thanks.
Yes, you need a power connector from your PC as well. Since your PC has SATA already, it would be very unusual if there weren't an extra power connector already inside your case, most likely on the same cable that powers its current hard drive.
If not, you probably have a 4-pin Molex connector that can be converted to an SATA power connector using this:
