The Noctua NH-C14 is a dual fan CPU heatsink designed to have fans above and below the bulk of the cooler as opposed to on the sides, a classic setup that has not had much usage on high end coolers recently.  That orientation will lower the depth requirement of your case though  the cooler stands tall enough that there should not be much clearance difficulty with a crowded CPU socket. Silent PC Review has no problems recommending this heatsink, either with a single fan installed or with both running to cool a high load CPU.
“Noctua’s NH-C14 is a big, beastly follow-up to the popular NH-C12P top-down CPU cooler. Armed with a bigger fin stack and two 14 cm fans, the C14 is the first down-blower cooler that truly competes against the against the formidable side-blowing towers that have taken over in recent years.”

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