I'm in an environment which appears to be vastly hotter than OFSO's. The only thing I do is make sure a machine is not sitting on a hard surface: if you can space it a couple of cm above the hard deck, convection will take care of the rest.
I've also converted a couple of machines to liquid cooling. Only for the experience, I didn't think it had any absolute benefit until recently. Right now, I'd go for liquid cooling simply because it leaves the case generally uncluttered, and you get a good exhaust fan for free. I've never had a liquid system leak, even in the early days when I used them simply to say I had one. In my particular case, the graphics cards are a greater concern than the CPU. The CPU is the low-cost bit.
Finally, CPU's are cheap. Why not have one in stock?