The iMac CD Firmware Update application places new firmware on the CD-ROM drive to reduce the amount of disc vibration. This vibration is typically caused by unbalanced CDs spinning at higher speeds in the internal CD-ROM drive. This vibration may cause the drive to have difficulty reading the CD. The update also corrects an intermittent delay that can occur on some iMac models when there is no CD in the CD-ROM drive. This update replaces "iMac CD Firmware Update 1.0".