The TX series is an update of the older SX series, all of which offer open airways and good cooling. They're only as quiet as the parts you put inside, with no attempt to baffle or dampen noise at all. Not that such attempts are really very successful, at all, but a case like the Sonata will be slightly quieter than a TX model with the same parts inside... It'll also run warmer.
Component selection is the key to a quiet computer. It's a lot easier to prevent noise than to kill it, and cases that breathe well allow for wimpy fans that just won't deliver in more restrictive boxes...