Originally Posted by
Drudgery
In short, no. A number of overclock benchmarks have been done on the standard stock cooler you get with the CPU. Having said that you can still do some limited overclocking with that processor you've bought and you could get a maximum of 3.8GHz running on all four cores, provided your cooler can support the temperatures the CPU gives off.
If you do plan to buy an after market cooler to overclock your CPU then i'd suggest shopping somewhere in the UK where they sell OEM 2500k's which cost about the same as a retail boxed 2500. Aria, Overclockers and Scan sell such items. I'd personally choose either Scan or Aria looking at their overall prices.
In terms of PSU's, both the XFX Pro Core 650 and Corsair TX650 come highly recommended and both perform similarly and are priced similarly as well. Prices for these units can very between £60-£70 depending on the retailer. However if you want to go cheaper, the cheapest i'd go with would probably be the Be Quiet Pure Power 530W PSU @£55. They are known for their quality PSU's, so you shouldn't worry about the brand and they have enough connectors to support GPU's that require x2 6 pin PCI-E sockets, such as the GTX460.