I have a Corsair 200R Carbide Series Compact Mid Tower Case
Corsair 200R Carbide Series Compact Mid Tower Case Black No PSU - CC-9011025-WW/BULK - Scan.co.uk
So the hot air produced by the heatsink fan blows downward but the vents is on the top and the back ?
Does your case get warm or hot when its in operation ?
Also some manufacturer oem fans arent worth jack ****.
AeroCool DS 120mm Blue 120mm Patented Dual layered blades with noise and shock reduction frame - Newegg.com
With something like this and the heatsink I recommended with thermal paste.
That should be enough or better than a basic water cooling setup.