SPCR

Hello, i am searching the components to build my first mini pc.
I alreadu have the motherboard, Asus P8H77-I

Motherbord: Asus P8H77-I
Processor: Intel Core i3-3240 3.4Ghz 3MB
RAM: Kingston HyperX DDR3-1600Mhz 2x4GB
Hard drive: Western Digital Blue 2.5“ SATA III 500GB
Case: Realan E-I3 with 120w link:http://www.minicase.net/product_E-I3.html

Core i3-3240 has 55w, the case has power enough for this?
I will buy a silent CPU cooler and i need to know to height.

Thanks a lot

I don't know this case but it definitely has enough power (assuming the rating isn't BS).

Considering you're planning to use a hard drive instead of an SSD, I assume you're on a budget and don't need the best performance. So know this:
The i3 CPUs are expensive. And the one you picked even more so. It's typically not worth paying for more than the cheapest i3 in the same series (the 55W models in your case). Also, the cheaper Pentium and Celerons are sufficient for most people and better value.
And most people have no use for so much RAM.
Most people would prefer to settle for a slower CPU, less RAM in exchange for an SSD.

Especially with a slow fan, you will hear the hard drive and it will get hot.
If you can't afford an SSD and have no experience with this case, I recommend you try the stock heatsink first (assuming your case is tall enough). You may find the noise to be tolerable, especially if you underclock. A third-party heatsink would make more sense once you'll be able to afford an SSD.

On the CPU, I can see some chose the Intel Core i3-3225 for the intel iGPU HD4000, but i dont see the point of Intel® Core™ i3-3240 Processor, comes with HD2500, just slightly higher cpu clocks that to me its not worth it, i second Hfat advise into looking into pentium/celerons like Intel Pentium G2120.

On the Case, im not familiar with it, nor i know its clearance for a CPU cooler, but one that should fit out of being similar height to the stock is Scythe Kozuti Low Profile CPU Heatsink. On the case i would prefer something like Antec Mini-ITX Case ISK110-VESA, that comes with 90W psu and can hold 2x 2.5 hdds so you could end up with a ssd + mechanical hdd for storage.