How come I can only burn cd-r at 4x, not 20X

[mmoran27]

Yesterday I burned a dmg file (200MB) to a cd and I was only given 4X as the fastest speed. I thought the SR MBP is supposed to burn these at 20X?

 

[deadpixels]

superdrives can burn CD-R's at 24x. maybe the superdrive is adjusting the burning speed according to the quality of the media?

 

[Flyinace2000]

My first suspicion would be the media. Also, which softwre are you using to burn? I know when i burn a CD with Toast 8 it tells me both current burn speed and AVERAGE burn speed. I am not sure which one OSX reports while burning. Average speeds is always less since it takes a while for the CD to spin up to "top speed". OR was you laptop plugged in or on battery, could it be a power management setting to conserve power when on battery?

 

[Trepex]

superdrives can burn CD-R's at 24x. maybe the superdrive is adjusting the burning speed according to the quality of the media?

I suspect you are correct. Lots of drives do this based on what they determine the media can handle. Try different media rated for 24x perhaps?