According to ABit the board can handle dual core CPUs
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Processor
- Supports AMD Socket 939 Athlon 64/64FX & Athlon 64 X2 dual-core Processors
- With 2GHz system bus using Hyper Transport™ Technology
- Supports AMD CPU Cool 'n' Quiet Technology
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In order to notice a substancial boost in performance you would probably need to go up to at least a 4400+. New Egg has them for about $200 for OEM box. 4800+ OEM is $268.
Linkie