Intel Boxed Pentium 4 2.6 GHZ-HT 512K 800 FSB S478 ( BX80532PG2600D ) Cache Memory: 8KB L1 Data Cache; 512KB L2 Advanced Transfer Cache Featured Technologies: Hyper-Threading Technology (HTT), Hyper-Pipelined Technology (HPT) Multimedia Extensions: MMX, Streaming SIMD Extention 2 (SSE-2) Form Factor: 478-pin PPGA FC-PGA2 Socket 478 Compatible with Windows XP, 2000,Me, NT, 98; Unix