This one. With the right fan (just choose a 92mm silent one) it will be virtually silent plus if you overclock it will still be ultra quiet. I have one on the 670J prescott (supposed to be the hottest Intel) and it never goes much beyond 50c on full load. Much better than the Zalmans I have owned as they are noisy and fan mods are hard to perform on them.
http://www.thermalright.com/a_page/main_product_xp90C.htm
Check their url out before ordering in case your mobo is one of the ones listed with clearance issues.
ThermalRight XP-90C (Socket 754/939/478) Heatsink (HS-022-TR)
Users longing for an all copper, high performance heatpipe solution can wait no longer as Thermalright has announced their latest incarnation, the XP-90C. Featuring compatibility across multiple platforms, the XP-90C is suited for today's hottest running processors. Weighing in at 690 grams, this air-cooled monster means business and demands a high performance fan as its mate.
- All copper design for maximum performance
- Multiple heatpipes for well spread heat around copper fins
- Soldered fins to copper base to make effective contact
- Compatibility across multiple platforms (socket 478/754/939/940)
- Enormous wingspan gives extra cooling to MOSFET or NB chipset
Full Specification
Price: £26.95 (£31.67 Including VAT at 17.5%)