Hanover  - External burners in the slim line format are well suited for any laptop's travel bag. Yet it's important to give some consideration to how the external drives will draw their power, says the Hanover-based computer magazine c't.

The magazine recently tested six slim line models priced between 60 and 110 dollars. Five of them required no separate power supply and were able to run using the computer's U. S. B port.

The latter is practical, if the burner is to be used on the go and away from any wall sockets. There is a catch, however: the c't study found that most devices draw more power via the USB connection than is actually allowed by the USB standard.

While this did not create any actual problems during the testing, it still has the potential to cause trouble during real life use. Buyers are advised to test the interplay between the external burner and the mobile computer using the USB quickly after purchase. If the computer cannot handle the strain, the burner should be returned.

Many slim line burners can also be operated with a separate power supply. Yet not all models include a power pack with delivery. In those cases it must be purchased separately. Because of its construction and relatively light weight, the slim line drives are well suited for mobile use.

Even so, they burn no faster than 8x speed, while larger models in what is known as half-height format can provide speeds of up to 22x. The slim line burners are quieter, however. The slower write speeds also minimize the risk of write errors. Even so, users with stationary setups are probably better served with a half-height model. (dpa)