So I am building my first PC, and I was planning on going for the i7 2600k, but with the new ivy bridge, a lot of my friends who have already built their PCs had advised me to go for the i7 3770k. I understand Ivy Bridge is updated and supposed to be better, yet I am also aware of the heat problems, especially when OCing (I don't plan on OCing so far, probably no higher than 4.0). So, if I have an aftermarket HSF, the Noctua NH-D14 specifically, will I still be experiencing heat problems? Should I just go for the Sandy Bridge?
Intel's Core i7 2600K is a great processor, and if the 3770K wasn't out, I would have no problems recommending it to you. But, the problem is that Intel have released the 3770K, and it is definitely the best bang for buck you can go for.
It does get a bit hot when overclocked, and under strain, but this is mostly when all 8 threads are being utilized at 100%, and for gaming and general use, this is only a tiny portion of its use. If you were using it for video editing, or something equally straining, then you might think twice. But, you've said you're only overclocking to 4GHz, and at 4GHz, those overheating issues don't really pop up.
If you were pushing it past 4.5GHz (up toward 5GHz) then yes, it would be a huge consideration to not go for the 3770K if you were worried of overheating. But, these days, getting an Intel-based CPU to get hot enough to run into problems, is hard, unless pushing it past some serious boundaries (not only speed, but voltage).
I definitely recommend you go for the Ivy Bridge-based 3770K.