Toxic is very loud. It is the fastest of all 280x but I would advise against it cuz of noise. Just get the Vapor-X instead. Did you consider the Dual-X R9 280x? I went that route cuz it was cheaper and quieter, and games won't really be able to tell the difference.
Here is info on Vapor-X noise:
http://www.anandtech.com/show/7406/the-sapphire-r9-280x-toxic-review/4