1950 Fan Noise Linux vs Windows

We have about 75 servers running Redhat EL 4 and the fan noise is very loud even when the system is not loaded. We also have 25 of the same servers running Windows with a full load and they are relatively quiet. What gives? Does anybody know a fix for this on the Linux side, a patch, BIOS, etc. I've seen other posts on the internet but no solutions. Any help would be greatly appreciated.  Thanks.