Many CPUs come with promotion that they can be overclocked and play games faster.
The black edition of Phenom II X4/X6 can be overclocked up to 5GHz.

Linux boasts of using minimum hardware requirements.
So, does it mean overclocking is needless for linux?

Many people said overclocking can harm your CPU, but those who did it said that as long as you can make sure its temperature is not overheating, it is worthy to do it to enhance your PC's performance.

honestly i would say that overclocking is almost never actually necessary imho the relatively modest boost in performance doesn't in my opinion outweigh the risks of damaging the machine, but of course if you are one of those that just wants more 'horespower' out of what you bought then there are safe ways of overclocking a machine

as for linux's boast of running on low spec machines, while that isn't a false claim, some of the more modern desktop environments provided with linux distributions require a whole lot more specs then the bare minimum to linux system with a text console or a stripped down gui that does nothing but draw windows around programs, so you might benefit a bit from overclocking in that department, but if i were going to overclock anything it would be the video card, not the processor since that is where most of the heavy lifting is done with 3d graphics enhanced games/desktop environments.

From personal experience, the days of getting a big bang from CPU overclocking are pretty much dead. Yes, it can still be fun, and can give a boost for some number crunching apps, but in reality for games the performance boost needs to be increasing memory and GPU. I have run a variety of games, and in the DOS and early Windows days, CPU overclock was easier than buying a new CPU. Then the new crop of Geforce and ATI cards came out to allow overclocking. That boost was way better than a CPU overclock. These days I don't bother with either. On Slackware64 with a dual core AMD64 2.4GHz, 2 GB DRAM and a Geforce GT430, there are very few games that don't run well enough at stock settings and that includes via WINE.

I've overclocked my quadcore Intel i5 from 2.8 to 3.4. Whether or not it made much of a difference is hard to tell, but I can certainly compile software quickly and it doesn't hurt game performance in Wine. Things like Rift look nice on near ultra settings.

overclocking a cpu isn't much different in concept then putting nitrous in a car engine, it can increase performance, but unless you're a racer you don't need to be doing it since it can also damage your engine, same with a processor overclock, unless you are looking for something abstract like a few extra fps in your game or a slightly faster compile then go ahead and overclock, but do so at your own risk..

I like the car analogy. What's the difference of 0-6-mph in 5 sec versus 3 sec? For example, a production Ford Mustang vs SSC Ultimate Aero? I can afford the Mustang! And I still get a bit of speed fun on the highway. The Aero won't get me to work any faster in traffic either!

CPU and GPU overclocking is like that. Its nifty to get a boost, but unless you are talking at least 10-20% more game fps or cutting a 1 hr compile to <30 min...is the damage risk and money worth it in the long run (I've seen what happens when fans and cooling systems go out)? I upgraded from a 7600GS 512MB DDR to a GT430 1GB DDR3 for $79US. Overclocking the CPU and GPU would have cost much more for far less performance.

I honestly wouldn't bother with it. IMO these days it's more about number of instructions per clock cycle (and number of cores) than number of clock cycles per second…

A side question,
AMD comes up with APU, integrate graphic into its CPU.
Do you think this is a better product than having CPU and GPU separately?
Intel too has similar product.
At this moment, APU or CPU+GPU to choose?

APU saves your money, this is the obvious advantage.
Many reviews say that APU's performance is not losing to CPU+GPU.

5GHz? With phase change or liquid nitrogen cooling, yes. On water cooling....maybe. With air cooling? Nope, not happening.

Nobody with half a brain uses liquid nitrogen for anything apart from 'how far can we push it' and setting benchamrks. The only people hat play with phase change are heavy overclockers. Water cooling is more common, but still mostly only heavy overclockers, with a few underclockers/silent computing types as well.

4GHz is pushing it for air, but its do-able with decent coling, a good board and some knowledge of BIOS settings.

Yes, you wont 'need' to overclock to run linux at all.

It can shorten the lifespan a lot, if you push the voltage to hard. Even if the CPU isnt overheating.

A minor overclock is fairly sane, pushing things to within an inch of its life is asking for all sorts of trouble.

Bad analogy.

*blinks* Car analogies can be OK, but in this case its not working.

Sure, if you have a car thats a lot faster (for whatever reason) its not going to really get you to work that much faster. Thats due to other road users and road rules though, if you didnt have safely, other user or legal issues then a faster car could get you work faster.

I find it interesting that you think that a 10-20% increase in FPS is worth it, but you want a 50% decrease in compile times.

How would overclocking the CPU and GPU 'cost much more'? If your silly enough to blow the system it would cost more, but sane overclocking isnt that risky.

I'd guess that you would be talking about for FPS (or gaming in general) performance, as just changing video card isnt going to help general CPU user performance at all. No idea why you got a GT430 for gaming anyway, theres much better gaming cards for not much more cost.

I really dont like this 'combine the CPU + GPU' for anything apart from basic desktop use. For gaming in particular, its fairly crap (virtually ANY current GPU is faster than the AMD or intel intergrated into the CPU video chips).

Funny that you would bring up the AMD APU on an overclocking thread....the AMD CPUs with APU are fairly 'low end' CPUs without much processing power.

So I should avoid buying APU notebook or desktop?

Depends on what you want to achieve. If you only use the machine for some everyday stuff like watching videos, surfing the net or do some office work you will be perfectly fine with such an AMD processor. If you need more CPU power you can go for an Intel Core i system with integrated CPU. If you want to play modern games you should better buy something with a dedicated graphics chip/card.

Crossfire worths or not?
Expensive, why need it?

Agree on the APU systems. Though I have to point out that generally with the 'normal' (not low power) AMD systems vs Intel you tend to get a more bang for your buck. Once you go over about $300 on the CPU alone, intel is the way to go, but for more reasonable priced systems AMD is very good (but you knew that anyway, didnt you TobiSGD? )

I'd still advise that people avoid intel 'sandy bridge' systems using the intergrated video. Its supported better now than it was a a year ago, but its can still cause problems for people who want to run older kernels and xorg-server versions. A cheap video card is easier to deal with, and wont really cost you much more in power consumption...low end cards idle at very low power levels.

AMD/ATI crossfire (and nVidia SLI) is a way of hooking up and using multipule video cards to increase the GPU power.

Only ever used by gamers and people who like to have the most 'top end system' they can get, without caring about costs.

LOL, yeah, I know that (running a AMD 6-core CPU in my main rig). But it is not only bang for the buck that you will get with AMD, it is also features. At the time I wanted to buy a new notebook I found out that in my price-range only AMD had support for hardware virtualization.