Why is this motherboard so cheap?

I have a question, why this motherboard is so cheap and why should I not buy it for the same processor Core i5 2500K ? here's the motherboard http://www.microdirect.co.uk/Home/Product/54843/Asus-motherboard-P8H61-MX-USB3-SI-LGA1155-mATX .
Sorry for mistakes, English is not my native language.

That would be the H61 chipset, they have less features than boards with H67, P67, or Z68 chipsets. One of the biggest differences is the single PCIe x16 card slot with only two other card slots. If the board has everything you would need, there is no reason why you wouldn't buy it.

The H61 chipset doesn't support baseclock overclocking past the maximum turbo level. That is to say, the highest overclock you could achieve is 3.7GHz.

It's also a micro ATX board so there's not many expansion slots.

The computer I built for my parents has that exact mobo, it's excellent value for an i3 or locked (I.e. non-K i5). But if you pair it with a K series processor you're not getting the maximum potential out of the CPU.