Slight deviation, but how quiet is the 7990 on air? I've been looking to replace my 7979 with one as they are dead cheap at the moment.
If you use my bios, undervolt and have good case cooling then it runs pretty quiet. On Auto fan if you can keep it between 80-85c then the fan speed stays quiet low. Mine used to operate in the low to mid 80's range when playing BF4 with vsync off and the noise was pleasant. Beyond that it did get noticeable.