Cooler & case fan for a i5-750-powered new rig

Hi,

I finished setting up my new rig a few days ago. I've been monitoring the temps since then but I'm quite disappointed. It seems like the stock cooler is a piece of crap. It keeps the CPU at 40 on idle and at 75 on full load (with turbo boost disabled).

So, I'm looking for the following to improve the case airflow:

1. - a back-case fan (there's already a 14 cm front one which came with the case).
It should fit the following requirements: 12 cm diameter, high CFM and low noise.
I checked this review - http://www.overclockers.com/65-fans-tested-megahalems/, and spotted some good candidates but would like to see your suggestions, and if there are others not covered by the review, please share from your experience.

2. - a good CPU cooler.
The criteria here is also high CFM, low noise, low profile, not too heavy (around 500g) and keep the processor decently cool if overclocked close to 4GHz.
I tried to represent the available space the cooler should fit in the picture below.



So, if you have the same mobo or tested a lot of coolers I'm waiting for your suggestions.

tnx

What are you looking for in terms of price? There are a lot of options, but it will probably end up coming down to which of the big air coolers you think looks best for the price.

I didn't think of the price too much. The case fan is easier to choose. Silence is the most important. I just want to see what people recommend based on what they own.
As for the cpu cooler, the expensive ones are bulky and tall so I don't think they will fit into the available space. The compact ones are more suitable, like the Cooler Arctic Cooling Freezer 7 Pro rev. 2, which is one option I'm considering and is priced around 40$.