Many motherboards now ship with an on-board SATA or even PATA controller that performs hardware RAID. These controllers are useful, but may not offer some features available from an add-on card (which may also be newer, faster, support more drives, etc.)
The bad news begins when a user purchases an add-on RAID card manufactured by the same company as the on-board controller. The add-on card typically ships with its on-board boot BIOS enabled, and when installed, it will compete with the native controller for the system's boot resources. The result may be a system that doesn't boot from the new controller, a system that doesn't boot, period, or even a system that hangs hard before it gets out of POST.
If you're planning on replacing the functionality of an on-board RAID controller with an add-on card by the same manufacturer, the first thing to determine is whether the native controller can be disabled through BIOS—either its own BIOS or the system BIOS, depending on the level of integration that the motherboard manufacturer has employed. If you must boot from your motherboard's RAID/SATA controller, disabling it is obviously out of the question. And with some add-on cards, the BIOS cannot always be disabled, so you'll be in a catch-22 unless you opt for a different brand of add-on RAID controller.
One board maker that I've noticed is particularly problematic in this regard is actually one of the best controller manufacturers: Silicon Image. A motherboard with a native Silicon Image RAID controller will clash with another Silicon Image controller if the second one has boot support enabled. Fortunately, many of Silicon Image's add-on cards do allow boot support to be disabled. If you can't bring the system up long enough with the card in to set that feature (because of conflicts), you might try mounting the card in a different system, changing its CMOS settings to disable BIOS, then plugging it back into the system you intend to use.
About the author: Serdar Yegulalp is editor of the Windows Insight, (formerly the Windows Power Users Newsletter), a blog site devoted to hints, tips, tricks and news for users and administrators of Windows NT, Windows 2000, Windows XP, Windows Server 2003 and Vista. He has more than 12 years of Windows experience under his belt, and contributes regularly to SearchWinComputing.com and SearchSQLServer.com.
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