The Tbird produces an Extreme amount of heat.. to add a Pelt would add an extraordinary amount of heat into
your case and surrounding area... not to mention you are approaching the Point of diminishing returns when you
try to get bigger than an Alpha....
If you can't expell the heat fast enough, the pelt will fry that Tbird, and this includes the Case ventelation
which I think you'll have a hard time removing the heat....
The Alpha seems to be your best bet.. it's the most efficient, and if you mod it so you can use a larger fan
you might be able to keep noise levels down as well as getting some extra CFM's....
I'd suggest if you want Really cool Temps for that Athlon you go all out for a water cooling rig...
Craig