<< There is no backupsolution on earth for that level >>
Of course there is - it just isn't cheap. Do you really think that organisations like idrive, geocities, aol, yahoo, etc. don't backup their databases, users' file stores, pending e-mails, and web pages? I can assure you that they do, and they have far more than 800 GB of data.
Besides RAID or mirroring is no substitute for backups. What if a virus trashes your files - your mirror will be trashed too? I just have to wonder what you will be storing on those drives when the contents can be so easily recreated that you have no need to backup.
<< Overclocking? Again you're insane...
who cares when its 110% stable >>
How do you know it's stable? Do you have access to Intel's chip testing equipment?
Or have you just run Q3, Prime95 or 'CPU stability test' - because I can assure that they do not prove that your system is stable. I overclocked one of my systems by 13% (Intel) - it would run Q3 and unreal flyby for days without crashing. I ran Prime95 torture test for 3 weeks continuously without a reboot, with no errors detected. Despite this I still found several programs that would crash, and crash regularly but unpredictably - crashes which miraculously disappeared when I returned to normal clock speed.
You're overclocking and running encryption - you're begging to lose your data: a single bit error in an encrypted file will make the entire file unreadble.