IBM 44E5181 INTEL XEON X5550 QUAD-CORE 2.66GHZ 1MB L2 CACHE 8MB L3 CACHE 6.4GT/S QPI SOCKET-B(LGA-1366) 45NM 95W PROCESSOR ONLY FOR SYSTEMS X3550 M2, X3550 M3, X3650 M2, X3650 M3. REFURBISHED. IN STOCK.