To keep it short, I'm in a situation where my only option is to have a 4u rack case to put a 3930k CPU + ASRock Extreme6 motherboard into, and I can only use air cooling. The problem is, all high end air CPU coolers are about 5-10 mm too tall to fit into the case. I've gotten to the point where I can get everything in the case with the steel lid closed, but the lid would be pushed (i.e. slightly bent) upward about 5mm by one of the fans on the CPU cooler. The cooler is in the very center of the lid, so it's the least stressful, but it's still a noticeable amount of force added from the cooler having to push up on the lid. Thus, there would be additional force applied to the motherboard/CPU, though I haven't tried calculating how much. It isn't a ton.
So my question is, does anyone have an idea of how much (if any) extra force can be constantly applied onto the CPU/motherboard without problems? My only real alternative is to just rest the lid on the case, and tape it down on all sides. I need to squeeze every bit of cooling I can get into this machine, so a smaller cooler is not really an option.
The amount of force applied is far less important than the application angle. CPU coolers use opposing spring force to equalize force over the entire area of the CPU heat spreader. Applying an external force is almost certain to redistribute the applied force in a negative way causing uneven heat transfer. 5mm isn't "slight". Find another solution.