Ahh, ok. So you probably mean the extra IDE ports which come as part of the ATA RAID. Usually, it isn’t recommended that you connect a DVD writer to one of these. For some reason, performance tends to be quite awful. The usual symptoms are that you are only able to burn at really low speeds (4x or so). It is usually observed with extra IDE ports using a Promise IDE controller.
Your IC7-G doesn’t seem to be using that chipset for those extra IDE ports, according to [link=http://www.abit-usa.com/products/mb/techspec.php?categories=1&model=4]this[/link] so maybe you can give it a try and see if it works for you.
One way to test is to use Nero CD speed to do a burst rate test. You need to put a disc which has already been written (non-blank) to in the drive to run that test. If you get a burst rate of at least 24MB/s, you should be able to burn at 16x. You can also confirm it by using the “simulate” option of Nero CD Speed’s “create disc” tab to burn a 16x DVD-R disc. What that does is that it pretends to write a disc at 16x but doesn’t really write to the disc at all. The burn graph will tell you if it can hit 16x. Note : the “simulate” option doesn’t seem to work with DVD+R discs.