Dont bother with the stand alone, self contained single piece units, they promise massive BTU values, but are noisy and pretty hopeless. Main reason they are hopeless is you have to duct the hot air outside (via a tumble dryer type vent, or by having the pipe handing out of an open window)... Well for every cubic meter of hot air you blow out of the room, more hot air will leak back into the room either from the hot outside (from having window open), or from other rooms in your house. (Its not like your going to create a vacuum in your room, air pressure will equalize by replacing the air you vent out, with fresh air from outdoors)
Split units work really really well though, because they get rid of their heat with liquid coolant, and recycle the air inside the room being cooled, without the need to draw warm air in from outside, or other rooms. The end result is split AC units will reduce the temperatures MUCH faster, and then switch to fan only mode (saving a ton of power), until the room starts heating up again, at which point the compressor will come on again and it will cool again).
The only time the single part "complete" package AC units really work is late in the evening when the outside temperature is already falling, so as the warm air from the AC is vented outside, cooler air is drawn back into the room aiding the cooling process.... Using a fan at the window is only slightly less efficient than this though
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Insted of the heat coming from your PC case its going to be coming from the rad.
