1U rackspace cooling for i5

I'm thinking of building a music computer into a case with with a couple of piano-type keyboards for live performance. It will be a fairly large case, and I'll be able to move a lot of air through it, but in the current design the cpu itself has to fit under the second keyboard. The clearance is a little over 1 rackspace in height.

I have seen very few low-profile 1156 coolers, and no solid confirmation that they will be able to keep this processor cool in regular use. I might eventually like to overclock a bit too, but maybe that's completely unrealistic.

I currently run a Core2duo at a constant 55-75%. If it get any higher, I get dropouts. Music is hard on a processor, as it never gets to rest, although I'm sure gaming suffers from the same issues.

Any thoughts welcome.

thanks,
-eric