應該是那個人表達跟你想的不一樣，實際上只有DVD-/+R支援4X

http://sony.storagesupport.com/dvdrw/dru500adwn.htm

Firmware Upgrade 2.0G
1.Allows your Dual RW drive to record at 4X on 4X compatible DVD-/+R media.
2.Improves reading and writing performance and reliability.
3.Reduces vibration noise for the discs with unbalance or eccentricity.
4.Improves audio playback on written discs with stand alone systems.
5.Improves reading and writing performance with 8cm DVD-R/RW.

2.0G在我的500A上只是能在2.4X速度使用4X +RW罷了(2.0F是根本不能用4X +RW，格式化會Fail)，且2.0G燒一些原本沒問題的4X +R會出問題，建議換回2.0F使用。