Well i have 2 asus GTX670 DC2 in SLI for several months and no problem, they are running cool and quiet... And i also really like the look of those cards! I can only recommend them...
Yeah, but you've chosen the loudest non-reference cooler for the 670 out there!
Plus - the Zotac is over 10 degrees cooler under load...
The best non-reference coolers for the 670 are the KFA2, Asus and the Gigabyte.
All are quieter under load than the reference design, and still a fair few degrees cooler even with a 100mhz factory overclock applied, whilst the reference design doesn't have one at all.