You can easily overclock it to 3200mhz without having also to buy a different fan. Just overclock your processor the way it has to go (following a guide and not just jump into the bios and only change the mhz!). So lock things, disable speedstep, memory 1-1 with bus speed etc. etc. Overclock in steps of 5mhz bus speed (is not processorspeed, your multiplier is 10.5). Stress your PC with Orthos for many hours to test stability.
For example my E6750 runs 2666mhz standard 1.30v. I can make it run at 2950mhz while still not increasing the voltage. But even increasing the voltage a bit won't use much more energy. My E6750 runs at 3200mhz with only 1.34v. That is little watts more for like 550mhz speed increasement!). That's not gonna blow your PC.
You will even do better and get more speed increase per volt as you have a 45nm processor. Mine is a 65nm processor.
I am sure you can overclock quite some without having to use more energy. 45nm processors like your E7400 are good at that.
Here two links that you need for overclocking:
Your processor: http://processorfinder.intel.com/details...Spec=SLGQ8
Thermal Specification: 74.1°C (so max temp measured with Realtemp = 74 degrees)
Thermal Design Power: 65w (is same energy use as mine)
VID Voltage Range: 0.85V – 1.3625V (max voltage your processor may handle = 1.36v)
And a guide to overclock: http://www.sharkyextreme.com/hardware/gu..._oc_guide/
But you can look on the internet for tons of other guides as well.
Half the people on this planet overclocked theirs already so it's not a PC freak thing. And Intel is even encouraging it.
Good luck overclocking, it's very safe if you follow the rules/guides.
Your intel fan will serve you well with the little overclock of 3200mhz speed, no need to buy a different one.