Is your CPU fan on backwards?
The fan should blow air DOWN not UP, pushing air down between the heatsink fins. If the fan is installed backwards - meaning sucking air up from the heatsink, youll have a problem.
As far and liquid cooling? sure its an option, but unless you live in the desert with no AC, or are over clocking, theres no real need.
Also, are you sure no wires are getting caught in the fan blades once you put the case back together?
Try running the PC with the side panel off.
Many people suggested I go with liquid cooling, but never did, I modified my case to allow more air flow. My PC now runs cooler over all, with the case closed, than it does with the case open. Its also alot quieter.. I have a total of 5 extra fans in my case, hooked to a controller so I can control the amount of cooling vs noise.
download speed fan, and manually crank up the CPU fan, you should be able to hear it roar to life.
Hope this helps.