Reusing old devices may sound smart but sometimes it's more trouble than its worth.
In order to properly set up some sort of decent CC/CV supply not only you'll need CC/CV modules, but: voltmeter, amperimeter, connectors, switches, box, etc. Of course, you may not need all of this stuff.
A good looking new module: B900W NC DC Constant Current Power Supply Boost Module Ammeter; having a a high output voltage allows us to, for example, run more led stuff in series. If you have buck needs, you can also add some sort of buck unit to the equation.
Now, take a look here: KPS3010D Adjustable High precision double LED display switch DC Power Supply protection function 30V10A 110V-230V 0.1V/0.01A EU
Looks like a real bargain to me… 
EDIT. Recently reviewed here:
These strips are resistor ballasted to operate safely with a standard voltage controlled supply, generally at 12V, designed for the dumb end-consumer. Of course, dimmed they can be by carefully adjusting (reducing) the input voltage (something you may not be able to do on a PC PSU, but is doable on the commercial 12V units will34 does not seem to like).
Cheers ^:)