I wanna hook up 12v dc components to 120v ac. Directly splicing the power wires will fry the devices right? and i heard a power supply from a computer can b used as a converter? can ne one help me out with this plz

 

Hooking most anything that wants 12V DC to 110V AC will most likely destroy it. In some cases it will be a dramatic event resulting in a call to 911 to put out the fire or transport an injured person. Don't do it.

Computer power supplies do have a 12V DC output, however it takes a bit of work to convert them into a usable, general purpose power supply. Here's a link to a site with one example:

How to Convert a Computer ATX Power Supply to a Lab Power Supply (with video) - wikiHow

Use your favorite browser to find other sites, search for "converting a computer power supply".

Jim.