Motherboard doesn't recognize 1.5 terabyte hard drives

it is not normal -  i would suggest to check all connectors, and mountings.
remove /disconnect and inspect plugs and connectors
verify he did not update the bios -  same version ??

Replace the motherboard. Looks like an old Mobo that has limit of 500GB drive support.
Get the one latest.

can you perform a BIOS reset and whether the problem goes away or stays the same?

I have been fiddling with the system today, and realized that one of my 1.5 terabyte drives is recognized by the system correctly.  I tried it on all the SATA ports and it recognizes it on all connectors.  The other 2 drives are identical...Seagate Barracuda 7200.11 1500 Gbytes.  On any port, they are identified as 500 Gbytes.  Both have data on them when the system still recognized them correctly.  I don't want to compromise them or be forced to use them as 500 G drives.  Any more suggestions?  I'm stumped.   I'm going to look for a BIOS update for the motherboard.  It doesn't make sense that identical hard drives would be identifed differently.

if the BIOS recognises them differently, 100% chance the partition info will not be read correctly as well.

i think you should get an external case, and get your data off, and then do anything else.

Once we had here in EE a case where BIOS had limit to 2TB. Whatever the author did the limit size of 2TB was not possible to exceed.

but we have a 1.5tb case here. and i think the mobo is newer than the 2tb one (can you link that case?)

http://techreport.com/articles.x/7982/1

the BIOS is a Phoenix AwardBIOS - pretty robust.
its either the storage controller, or the BIOS or the Drives themselves.

since the chances of all the drives, even 2 drives from a 3 drive set, failing simultaneously is pretty low, i am inclined to think that its something with the BIOS.
thats the reason i recommended trying an external mount

i would try to get the data off first; then run a chkdsk on the drives..
starnge that w7 and Xp see them as 500 G
makes me suppose something happened to your board

that's why i ask to test on another pc..

This evening, I used a different PC to test the hard drives.  The one that tested correctly on the main system tested correctly on the second system.  Both of the other 2 drives, mind you the same model number and BIOS version (CC1H) read as 500 gig.  Is it possible that Windows 7 did something to affect the drives this way?

ok - that  at least clears something up : it is not the pc causing it, but something changed the disk or partition info.
seagate??  bad news coming to you  lookie here :  http://techreport.com/discussions.x/15863
maybe you should consider contacting them ?

Updating firmware could be necessary. If the drives are still on warranty then the shortest way to win is to replace them.

One of the drives contains a bunch of movies....the other one was the original WIN7 OS and a backup of my machine from inside my house (I keep the other machine in my workshop). The one that I reloaded
was a replica of the first drive...so I've zapped it at this point.  SInce it was the only one that was still recognized as 1.5 TBytes, I chose it for the OS.  The system seems to be running fine with it now, minus the other 2 drives .  I'm gonna contact Seagate as you'all have suggested.  I've not given up on my data yet...even though it's not critical stuff.  Thanks for the input.  

i concur, if the data is not all that important, getting them replaced would be the wisest.

Seagate has replied with this:

After talking with my Lead and looking for possible solutions. We have only been able to come to the solution, that some how the drives attributes got change upon the reconnect. The only option we can suggest is that you use our Seatools for DOS utility and try a set hard drive capacity to max procedure. This process might delete data, if you can access any of the drive data now I would suggest that you back it up, before doing this process. Below is the link for the Seatools for DOS, burn the .iso to a CD and then boot to the CD and do the set drive capacity. The process only takes a few seconds. After it is done if it worked you should see that the drive is showing the correct capacity. If it is still not then the drives will need to be returned for replacement, because the LBA is un repairable.

http://www.seagate.com/staticfiles/support/seatools/SeaToolsDOS217EURO.ISO

i'm anxiious to see if it fixes it

we are all waiting with you.
with crossed fingers :)

I ran the Seatools for DOS last night.  It's an ISO file that you extract to a bootable CD.  I connected "one" of the bad drives to my system in my house, not the offending workstation.  I disconnected the other drives as to not make a mistake of which drive I was actually working on.  The tool boots up in a DOS like environment.  Initially, it saw the drive as 500 G just as before.  Then, I ran the command suggested by the Seagate Rep, "set drive capacity to maximum".  The change to 1.5 T was immediate!  This drive was the one with the WIN 7 system loaded on it.  I tried to reboot the system (old box) but it still went through that vicious loop after displaying the initital Windows animation.  I then took the drive and connected it back to my house system with the original house drives reattached as well.  When I opened "My computer", I could see the data on the drive!  Obviously, there is some issue with the boot record, and the system may need a "repair" install run on it, but I think I'm out of the woods.  I plan to do the other one tonight which has all my movies on it.  Thanks for all the help.  I hope this info will be useful to soemone else, since there seems to be a lot of issues with the larger Seagate drives.  I really had to "dig" to come to this solution!  

i'm glad i found what was wrong...and i like you could recover all data; good to know!

it is good news indeed!

if you don't need more help - please close this question !

Forgive my ignorance.  I see how to delete the question, but how do I close it?

beside every answer. there is a link "accept as solution" and "accept multiple solutions"

to give all points to a single answer clink on the "accept as solution" link of the particular answer
to spread the points among multiple answers, click on "accept multiple solutions" of the first answer and then on the next page that opens, select the answers that you would like to give points to.

here the help file on how to close : (every user is supposed to have read them  - lol) :  https://www.experts-exchange.com/help.jsp#hs=29&hi=407