Not entirely true... you can OC a non-K cpu up to 4.2GHz via the turbo frequency. It is thermally limited (meaning it will down clock if it gets too hot), and it is load limited (meaning it will not go up to 4.2GHz unless there is a heavy load), but it is actually quite effective if you do not care to go nuts with a 4.5+GHz OC.
It is what I do on my system, and I actually like it because the power is there when I need it (gaming and video editing), but then goes back to a nice 1.6GHz idle when nothing is going on (which is handy as the system is on 24/7).
That being said, I am sure that the OP is looking to OC at a more regular set speed, and may want to get past that 4.2GHz threshold.
if you have an aftermarket cooler then you can keep the CPU cool enough to get a full OC with all cores under load with no problem. Mine benches at 4.2GHz just as well as a K series CPU at the same speed. Only limit is that I cannot break 4.2 which is plenty fine for most people.
And no, there are no stability issues doing this either as the mobo will up voltage if needed.
Agreed with Mauvecloud. You do not neet Z series motherboard since your processor can't be overclock. I myself going to get the almost same spec new PC but I go for B75 Mobo. Usually the life-span of my new PC around 2 years and so I don't mind much about the mobo.