|Are you sure you're stating your situation correctly??|
If the hard drives have no data on them and are not partitioned and formatted, or if they're partitioned but not formatted, or if they're partitioned using something the operating system doesn't recognize, if the mboard's bios is recognizing them, it's normal for them to show up in Device Manager and Disk Mangement but NOT in My Computer and Windows Explorer.
Can you see other drives in Disk Management
e.g. an optical (CD or DVD) drive, or nothing at all?
It is certainly NOT normal for you to NOT see the hard drives in Disk Management, or not see anything in Disk Management, if you can see them in My Computer and Device Manager.
Do you see only other drives in My Computer and Device Manager, or are you seeing the hard drives there?
Can you access the hard drives there?
Do you have only external hard drives, plugged into USB or firewire ports?
Have you by any chance re-loaded Windows from scratch?
Do you have other symptoms you have not mentioned? If so, tell us about them.
There are FAKED symptoms that can be installed by makers of what's generically called "rogue" anti malware software, merely by you visting a contaminated web site. If you have other symptoms as well, those symptoms produced by this are not removed properly by most legitimate anti-malware software. Along with those symptoms, you always get frequent messages saying you computer has malware and references to go to certain anti-malware sites, and there are often one or more icons that have appeared on your desktop that you did not place there yourself that link to certain anti-malware web sites. You must use software that specializes in getting rid of the FAKED symptoms and the software that placed them on your system - e.g. Malwarebytes, sometimes you need to run Smitfraudfix too.