07.31.07
Upgrading Gateway GT5404 Desktop Hardwares
Gateway GT5404 and GT5408 Desktop can accommodate up to Intel Core 2 Duo E6700 (2.66 GHz, 4 MB L2 Cache, 1066 MHz FSB)
GT5404 Motherboard model number: D945GCL
GT5408 Motherboard model number: D945GCF (almost identical to D945GCL but with built-in FireWire controllers)
Source:
http://support.intel.com/support/motherboards/desktop/d945gcl/sb/CS-026624.htm
