E4500 turn out to be a great when it comes to overclocking.
First of all download CPU-Z and RealTemp to monitor hardware and temperature.
Secondly download Prime95 which will allow to test the processor under 100% load also called stressing.
The best way to overclock PCU is to do so though the BIOS.
To start you can set FSB Memory clock mode to linked and increase FSB by 20-50mhz (that will decrease your ram performance for now). Load the system and prime95 and check the temperature. Here it’s done @2.75Ghz
Keep increasing the FSB until the temperature start to reach 67-70C as 72C is max for this Intel processor.If you can afford get different cooler.
After stable PCU, unlinked it from memory (you can also overclock the memory a bit 20-50mhz and give a bit of vol. between 1.8-2.2 – which is max BE CAREFUL!) I run my crossair PC6400 at 1000mhz (800mhz stock) 1.95v
My E4500 is now @3.25GHz (FSB 275×11) but I have seen people with some £20 quid worth of cooling push it towards @3.6GHz.
The current 3.06Ghz CPU gets quite hot after 3H of prime95 stressing. I ignore it as even playing latest games graphics card to most of the work. PCU shouldn’t be getting as hot