HiI have some cd-rws, rated 4x-12x, but my 4551 can only burn them at 10x. Why cant I choose any other speed? My old cd writer had 4, 8, 10 and 12.
There is only so much room for CD write strategies. Almost no one uses the lower speeds; actually many 12X discs I had did just fine up to 32X. You will just have to tolerate these limits until you get some current media.
CD-RW is different. They come in different revisions, marketed as US/Ultra-Speed and HS/High-Speed. They are limited to the rated speeds printed on them, with suitable burners only.
Software update as well as FW!