Being a crippled Wolfdale, an E7500 doesn't have the thermal loads associated with the quad cores.Just an average cooler will give an astounishing amount of performance. I have an E7500 running at 4.1 GHz in an old Gigabyte motherboard.
A zero cost idea would be to find an old cooler from an original 65 nm dual or quad core. The first and second gen coolers share the same design, but the first gen 65 nm heatsinks are twice as large as the later 45 nm heatsinks.
Do not exceed the Intel recommended 1.45 volt core voltage and keep the load temps under 70 C. With a halfway decent cooler, you will likely reach max voltage before max temps.