i7-980x downgrade CPU?- to run cooler, quieter fan speed

[JazJon]

For my home theater PC I'm using the Shuttle SX58J3 bare bones case.

http://global.shuttle.com/products/productsSupportList?productId=1389

I currently have the Intel® Core™ i7 Processor Extreme Edition I7-980X installed and it works/runs great.

I'm thinking that maybe this near top end i7 monster is right on the edge of running too HOT for my case.

My case has a built in CPU heat sink with heat pipes as you know. The Health Monitor BIOS settings has 5 options for fan speed.
Auto, ultra low, low, medium, high

-low is dead quiet, but my case will over heat and cause the video card to pixalate.
-medium is functional for heat, but the fan is too LOUD! (for the living room)
-Auto fan noise compares somewhere between low and medium speeds (most of the time), but it's variable and catches you ear when it changes up/down/up/down.

Since I don't need the horse power of the I7-980X what can I down grade too that will guaranteed run cooler resulting in a quieter fan set to Auto?
(other specs and manual are in the link above as well)

I already tried replacing the CPU paste with a top of the line brand. (no change)

Suggestions?

[Marcin]

Better change case for something bigger, with additional low speed huge coolers. I'm using CoolerMaster HAF 912. And then CPU cooler to something like Scythe Mugen (very good performance and quiet).

Artefacts from VGA card predicts card replace soon

Good thermal grease is reqiured. I'm using Arctic Ceramique 2 everywhere I'm repairing.