Had a Q6600 and a prebuilt with no overclocking. Electrical tape over two contacts boosts 2.4 to 3.0 GHz! : r/techsupportmacgyver
CPUs - works on LGA 775 motherboard Xeon E5420 Processor 2.5GHz 12M 1333Mhz close to Core 2 Quad Q6600 cpu : Buy Online at Best Price in KSA - Souq is now Amazon.sa: Everything Else
How did the Intel Core 2 Quad Processor Q6600 support 64-bit instructions? - Quora