-15C is obviously not possible. You should use HWmonitor or CoreTemp to get a realistic reading of your cpu temps. I think you probably meant Zalman CNPS 8000. Otherwise I do not know of Kalman. Also the Zalman CNPS 8000 is maximum socket AM2 compatible, so I am intrigued how you've mounted it on an AM3+ mobo.
Can you link us to any online page on Kalman CNPS 8000?
Although a recording studio would require a silent system, I do not know how well that cooler would do in keeping the cpu temps in check.
The cpu would only shut itself down when the thermal ceiling is reached. It should normally throttle and not shutdown.
so here is what we need; before we start blaming the temps to be a reason for the system shutting down, we need realistic temps from both of those softwares that I and Ewok mentioned. This might not be a temp related problem altogether.
Tell us about the ambient temps of your studio. At it's lowest fan speed and noise settings, on an average, the CNPS 8000 did not do very well with the cpus. Also, as I mentioned the stuff about the cooler being designed for the socket AM2 and that you have an AM3+ cpu, Share your full system specs. Like which Gigabyte mobo do you have.