I also have heard of this problem with the 'cuda IVs and a RAID setup. They posses an extremely low read time, but for some reason when being imaged, the controller has difficulty accessing the paired read heads.
They are great drives when used in a traditional storage configuration.
To paraphrase Seagate technical support, the Seagate is so fast that the RAID controller can't buffer the data quickly enough and so the disk has to read everything twice and hence runs much slower. So there you have it: the disk is so fast it is actually much slower. Seagate do not have a firmware fix at the present time as they claim they are waiting "for the rest of the industry to catch up". See this thread at Storage Review forums for more details. The problem has been reported on several different motherboard chipsets and several different RAID controllers. The problem is not specific to ABIT motherboards. Some people have reported success by putting the disks on separate IDE controllers. Seagate seem prepared to accept returns for users with this problem - contact customer support.
It's almost funny their response to this problem. I'm sure they could "slow" their drives down to allow for quality raiding.