If you have a loud machine and are willing to trade a little thermal conductivity for some serious sound dampening then check out Corsair's Carbide 275Q.   It is fairly compact, at 460x211x455mm but still roomy inside and can handle a 370mm GPU and a 170mm CPU heatsink.  Along with the sound dampening material, this ~$100 case comes with a PWM repeater you can attach to a fan header on your motherboard and control six fans. 

The Guru of 3D declared this a wise choice for someone looking for an inexpensive and quiet mid-sized system.

"The Corsair Carbide Series 275Q is a quiet mid-tower ATX case that matches minimalist design with whisper quiet operation thanks to built-in high-density sound damping panels."

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CASES & COOLING