I have had to RMA 2 x 680i AR's and 3 x 680i A1's due to bi-hourly BSOD's caused by the faulty and oh-so-breakalbe memory controller on that motherboard,
I'm sure almost everyone will agree with me when i say that the 680i has been proven NOT TO WORK (counter to your justification above) I'm not trying to put a damper on your project but seriously, go get another mobo if your dont want to have to deal with the crap that one will give you.
Thats not even considering the NUMEROUS issues the 680i has with quad cores (i always use core2 duo with mine), and I know your gonna say "oh well they fixed that with the a1 revision". errrr wrong answer they didn't, your clocks are gonna be limited and it'll be a darned shame with all that smexy watercooling your putting in.
I just hope you will re-evaluate your options on the motherboard and maybe realize that I'm not just telling you these things for fun, I seriously want your project to be successful

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