You could try swapping out the drive interconnect board. The blowers connect to it, and they have a habit of failing. I have two boards (different versions) one of them only powers one blower, the other doesn't power either. Maybe it can break so they run full blast too.
You might also find that the noise is actually from the PSU fans. I have two PSUs, one is pretty quiet, the other is like a wind tunnel. And the fans in them run a monstrous 9000rpm, so its a more likely culprit. The blowers only run up to about 4000rpm.