DVD SPEED

I was talking to a computer local manufacture yesterday and told me that when you buy a dvd player for your computer or even a Cd-rom when it says 50x for Cd and 12x for DVD. Its a big joke. He told me that it doesn't mean that it reads at that speend thats just how fast it spends. He told me I didn't need a 12x DVD which is fine I don't want to spend money on something I will not use.

He's more or less right.

The Dvd standard is close to 1250k/s. So a 1x reads any dvd at 1250k/s, 2x @ 2500k/s, 3x @ 3750k/s, etc. The Cdrom standard is close to 150k/s. A dvd 2x is comparable to a 17x cdrom. That 50x cdrom drive spins up (at max) real close to 5000rpm. The 'old' kenwood 72x cdrom drives spin up to about 1500rpm. I've not seen much info on how fast the dvd drives spin.

You can take a 50x cdrom drive and see about .5meg/sec diffference over a 40x drive. At those really high rpm, linear momentum really plays havoc, and no cdrom/dvd is perfectly balanced. Have you ever seen a gyro at 30,000rpm explode (literally) from coming into contact with the housing due to excessive g's?