Rimhill is described as 'sets the maximum cd-rom speed to a specified level in your drive'. There are three alternatives to Rimhill for Windows and Mac. The best alternative is DiscRotate, which is both free and Open Source. Other great apps like Rimhill are Nero DiscSpeed (Free) and CDSlow (Free, Open Source).
Nero DiscSpeed, previously Nero DriveSpeed, is a disc speed measurement and performance diagnostics tool. It reads the speed of a CD-ROM drive. Not included in the Nero 11 or later, is part of Nero Free Tools.
CDSlow is a program to control the speed of CD/DVD/Blu-ray drives. More precisely, to limit the maximum speed of the drive for reducing the noise, when it is not required to read the data very fast (for example, when listening a MP3 music).