My computer raises the ambient room temperature by about 4°F. I don't like it (in the summer)
Solution 1:
Turning off the fans, liquid cooling, etc does not reduce the total heat caused by powering the components in your computer.
If you vent the heat from the electronics into the room, you are going to raise the temperature of your room, regardless of the method used to remove the heat.
The only solution is to either turn off the computer or vent the heat out of that room.
Solution 2:
You need to take the heat out of the room...
... I use the mains water pipes as my heat-sink!
I have a slightly unusual set-up. My study was originally the kitchen which was relocated to an extension. As a result, the mains-water inlet still comes into the room. I have a water cooling system on an old machine that I want on all of the time and it's using an old Intel CPU that I should probably replace, but it works - it just generates a lot of heat.
My water-cooling pipes come out of the case and connect to a refrigeration pipe that I have wrapped tightly around the water-mains. I now have a huge heat-sink of underground water to dissipate my heat into! ;-)
Keeps the system almost silent (pump makes a very low amount noise, much less than a fan) and stops the room from getting warm!
Solution 3:
The amount of heat generated by your computer can only be altered by either using more efficient components (ones that generate less heat) or by removing components.
Heat is a byproduct of inefficiency, if you swap your CPU for one that consumes less power (look at wattage ratings) and remove extra items that consumer power (and in turn generate heat) then you'll find the temperature savings.
PC Cooling systems are intended to dissapate heat, not lower the total heat output. Disabling them will help keep heat in your system but could cause problems (fans are there for a reason; hot chips are unhappy chips). So unless you want to bring home a block of dry ice every day to offset the generated heat then there's not a lot you can do.
Now, with all that said, try buying a cheap infrared thermometer and use it to determine where the heat is originating. Components without fans will give you the best readings (the ones with fans will blow the heat away); take a look at your monitor, printer (laser especially), power bricks, and power-supply and find the worst culprits. You might be able to put the bad-guys on a seperate power-strip and kill power to all of them when you're not around.