I'm intending on overclocking my Intel i5 2500K to around 4.7GHz the cooling that I have is Cooler Master Hyper 212+ CPU Cooler as well as 2x200mm, 2x120mm and 1x120mm case fans in an NZXT Phantom case and mounted into a ASUS P8P67 Pro MOBO.
will the CPU be cool enough or should I consider clocking it to a lower speed?
YMMV, meaning that your chip might overclock more or less than average. I've seen a lot of people report 4.5GHz.
You can do some googling to find out the safe max. temp for that cpu. I see people talking about numbers like 80C but I don't know what the exact number is. I get a little scared before getting to that point.
Unless your running 2 very high end video cards, theres no reason to overclock it at all. Your just making more heat, higher electric bill and shorter lifespan of your components.
I run autocad and Revit, and they will use all the CPU horsepower you can get and cry for more. AutoCAD is basically single-threaded, and doesn't care what GPU you have, so the only way to speed it up is to crank up the clock rate of your processor. My current workstation is a little over 2 years old, an E8500 that I cranked up to 3.8GHz. I will likely build a new one within a year or so and I will crank it to about as high as it will go, and I will cry for more.
I don't think overclocking is automatically shortening lifespan, or at least not such that it matters to anyone. I've messed with cpu's running at stock speeds with stock coolers, and I've put good aftermarket coolers on them and overclocked them. The cpu at stock speed with stock cooler ran hotter than the overclocked cpu with good aftermarket cooler. It is possible then that the cpu at stock speed would have the shorter lifespan.
But for gaming, we may be at a point where cpu power is way ahead of GPU power.
I'll be using it primarily for gaming, first running a single HD6950 2Gb but eventually CrossFire HD6950's, I'm not bothered about going over 4.7-5GHz I'd rather have it be stable and last longer at around 4.7GHz then end up replacing it after 6 months cause I ran it at 5Ghz+
I have it at 4.7GHz with CM 212+ as well, I get less than 70 degrees celsius at max loads and voltage of 1.304v~1.360 (it spikes up to 1.360v time to time but only for a moment).
I can probably get it up to 4.8GHz or 4.9GHz, but meh I don't want to put in that much time.
But every chip is different, even though our setups are identical (even our gpu cards are the same). Your's might be able to overclock higher more easily, or yours might overclock less slightly. Only real way to find out, is to actually try it out.
Just avoid going above 1.4v and avoid going above 75 degree celsius. You can adjust the voltages seperately, so you don't hit that 1.4v to easily.