I wanted to share how I was able to format/partition my 3TB Seagate Drive with everyone as it was a hair pulling experience. Note that I have several workstations, OS's, and types of hardware.
I bought the 3TB Seagate drive and where I bought it doesn't matter. The point is that I brought it home and was only able to format 748GB, no matter what I tried. It didn't matter which system I put the drive in, XP, Win7 x64, Linux, and other various attempts to get the full 3TB. I tried disk management, MBR, GPT, and a few other nifty tricks to no avail. Disk Management under any OS showed only a 748GB partition, nothing else after it...even though I knew it was a 3TB drive.
I did the pointless route which included calling Seagate and HP but both quickly pointed fingers at one another insisting it was the other's problem and they haven't heard anywhere of this being a problem. They also wanted to charge me a nice monthly subscription to find out. Finally, I took the drive back to the place I bought it and plainly asked the vendor to format the drive to 3TB because they had a lab environment with many more machines and Operating Systems than I had at my place, which they had a motherboard, Vista, which had a BUILT-IN SATA HD connector. They had no issues seeing ALL the partitions I tried to create with the drive that weren't showing up on my hardware at all. They wiped those out, installed one full 3TB partition, and I brought it home. I changed my Disk Management within Win7 to GPT, disconnected the drive then reconnected it...everything was there, the full 3TB...where it wasn't previously. I copied data to it and made sure to back that data up on another resource.
I was told many things including that the drive doesn't work very well with external enclosures, doesn't operate as a master OS drive, and lots of other nonsense. Also, a lot of the forums I searched didn't have much information on how to deal with this situation - thus, I'm writing this to reiterate that it *is* possible to have a 3TB drive, fully formatted without multiple partitions, and the OS able to deal with it... even in an external enclosure. My BIOS on all my machines were fully up to date and within them didn't include any HD information so I figured that it wasn't a BIOS issue, at least to get this to work - these HP laptops were purchased within the last year. I have a few enclosures and I've plugged the 3TB drive into them without problems of the OS Win7 x64 recognizing it.
Note: I have not taken the drive back to older operating systems or other machines yet and I would think that being GPT ... they may or may not be able to read it, jury is still out. Therefore, I'm going to be delicate with the data on this drive and make sure I fully back it up before I take the drive and plug it anywhere. I'd highly advise the same.
The large success was the fact that the drive was formatted and partitioned - which none of my operating systems or machines were able to do. It may very well be a hardware issue or perhaps the issue with SATA enclosures where I originally tried in vain to format the drive. Perhaps if I had a machine that had a PCI or motherboard SATA controller than I should have plugged it into there and formatted and partitioned the drive as the vendor I brought the drive did... probably would have worked, just not from the enclosure which was the only way I had to format the drive.
In a nutshell, it appears that the problem was with the SATA controllers themselves within the enclosures. I wasn't able to easily find a SATA enclosure that was rated for anything above 2TB. However, once the drive was formatted and partitioned through the motherboard SATA, I was able to plug this SAME 3TB drive into those enclosures without a problem and use the drive. This also leads me to believe this isn't a BIOS issue as previously thought, nor an OS issue as Win7 x64 has no problem with drives of that size.
Seagate's Disc Wizard which came with the drive was pointless and useless, btw. It also only saw the drive as 746GB.
Words of Golden Wisdom: Never take ANY chances with your data. If your data is valuable enough, before you make ANY changes to your situation please please please make sure you've backed it up to another hard drive elsewhere and put that drive some place safe.
I hope this post helps someone else - if not get their 3TB working but perhaps also save their data and time.