Ubuntu :: Difficulties Building RAID5 Under 10.10 64bit

I recently went shopping at newegg for components for a new home server to fulfill multiple needs--chief amongst them to replace an aging old Athlon box which has been running a 4TB software raid for years now So I ordered an ASUS P7P55D-E LX mobo, 8GB DDR2, a core i5 quad-core, and 6 WD "green" 2TB drives (I'm more concerned with capacity than speed). I got it all assembled, using a 500GB 2.5" drive as the boot / host drive, a blu-ray reader, and splitting the 2TB drives amongst the 2 controllers (4 on the remaining ports of the x6 SATA controller and 2 on the x2 SATA-III controller, just not needing the SATA III capabilities). I plan to use Software RAID5 rather than the fakeraid that might be supported by the chipset. This affords maximum portability for the future.

At any rate, I installed 10.10 64-bit (Desktop), let it update, then installed mdadm and set about configuring the RAID5. I decided to use the nifty graphical tool. Last time I did this on my old Fedora box, it was all CLI.All seemed to be going well, and I was letting it fully recover / synchronize before setting up a filesystem (planning on ext4 this time). I kept an eye on it with cat /proc/mdstat.

After 20 hrs (averaging 25MB/sec on the sync...seems a bit slow, but who knows?)...it finishes and the RAID is immediately degraded with one volume (/dev/sdc1) marked as faulty and another volume marked as a spare. I replaced the SATA cables with brand new ones as long ago I ran into an issue like this due to a bad cable. Before trying again I ran the extensive SMART test and a read/write benchmark on each drive. They all checked out fine. So I started over and 20hrs later, same thing.So I shut down and removed the offending drive and started with only 5 drives. Another 19hrs go by and this one turns up /dev/sde1 faulty and another drive marked as a spare. That drive was fine before, and is on a different controller from the one that it was finding as faulty before.

Now I am suspicious that there is a larger underlying issue and that the drives are not bad at all. Should I have just gone with a 32-bit + PAE install? Does the 64-bit have known issues with the software RAID? Should I have just built it using the CLI? Looking online, it seems people are having success with the GUI tool. I don't think it is the GUI tool. Checking with mdadm, it seems everything is being configured right.