OEM drives

I assume you are buying a SATA HDD and Not an older IDE (PATA) drive.

To connect the HDD to the Motherboard you will need a SATA data cable (usually red, seen som orange and yellow ones). Most MBs throw in a couple. You should have plenty of Power connectors coming from the PSU. IF the PSU does not have any SATA power Connectors you will need a molex to sata adaptor (usually a 6" cable)

For an "older" HDD and/or older DVD drive you need the 80 wire (40Pin) Wide ribbon cable. Remember on newer MB - Only ONE IDE connector (only two devices).

For cables, you just need a SATA cable for that.

No drive I can think of would need anything other than it's data connection to the system. I suggest you do not buy a DVD or BluRay drive OEM though, as those usually would come with movie play-back software that you otherwise have to pay for. There are good free media players for DVDs but if it's only $10 difference or so, probably just as good to get a retail package.

If you get a bare bones video card, you would ofcourse need the cables and possibly any adapters to match your monitor.

Don't forget to check if your power supply has enough sata power cables.

If not you'll have to get a molex to sata adapter.

Thanks a lot guys, cleared it up well