Wednesday, May 25, 2016

Building A New Computer: Overclocking

Normally I would start a discussion about a new computer by talking about the case. But there is one topic that needs to be discussed first since the decision there has an impact on which case to choose. That topic is overclocking and as I explain it will become obvious why a decision to overclock or not has an impact on what case you choose.

So what is overclocking? It is simply running your device at a clock rate that is greater than the part is certified for by the manufacturer.

To put it another way. An Intel i7-6700K has a clock speed of 4.0GHz and costs $350 while an intel i7-6700 has a clock speed of 3.4 GHz and costs $315. If you could change the CPU clock to run the i7-6700 at 4.0 GHz you would have saved yourself $35.

Now most people that overclock start with the fastest device that you can get and then push it past that to get performance that you simply could not find stock anywhere. If you want to infer that there is a certain prestige that goes along with overclocking, you would not be wrong.

So since you are pushing the capabilities of the part are there any drawbacks? From personal experience, technical guides and even the chip manufacturers the best answer is no. But there are caveats that go with it.

Is It Safe?

If done right the short answer is yes.

I have overclocked systems regularly in the past and they have had long lives. (It is sort of funny that the system that I am currently having problems with is the first that I have not overclocked in years.) I can point you to anecdotal evidence of where parts of the motherboard that are not impacted by overclocking died before the overclocked memory and CPU.

The greatest impact to the life of CPUs and memory is the average temperature that they run at. In extreme overclocking you can increase the temperature that they run at. But if you plan for and do a good job of cooling you may have a 10% reduction in the life of the part. But put it in more understandable terms. Instead of the parts lasting 8 to 10 years they now last 7 to 9 years. Ask yourself this, will you still be using the computer in 5 years let alone 6 or 7? The answer was that you probably will replace it long before 7 years so the reduction in life will never be an issue.

Now I did say if you did it right. There are two sure fire ways to kill CPUs and memory. 

The first way to kill them is running them too hot for too long. With memory this is less of a problem these days. Memory that is designed to be overclocked will come from the factory with excellent heat spreaders/heat sinks. If you have any question about cooling, both of the major overclocking vendors also have fan hits to help those heat spreaders keep your memory from overheating. For CPUs you actually have to investigate cooling and which ones can handle the the extra heat. The stock cooler will not be adequate. The good thing is that now that Intel is selling versions of their CPUs that are intended to be overclocked they do not ship CPU coolers with them. They know that the stock one will not be enough and that overclockers will be planning on a third party cooling system. But if you choose an adequate cooling solution and make sure that it is installed and running properly overheating should not be an issue.

The second way to kill them is applying too much voltage. Since different types of memory and generations of CPUs have different voltage requirements and limits it is difficult for motherboard manufactures to prevent applying too much voltage while maintaining flexibility. The best thing to do is adjust first memory or CPU and then the other. Most guides for overclocking list a suggested maximum safe voltage for your components. As long as you are aware of those voltages and do not exceed them you will not apply too much voltage.

GPUs are very hard to break. Since Graphics Cards do not allow you to change out GPUs the BIOS on the card and the voltage regulators are tuned to the GPU spec and will not allow you to put in enough voltage to break them.

What Can I Expect?

The best answer is that you can expect the clock rate listed on the packaging.

For memory this is not a bad thing. Memory has been supporting overclocking longer than the CPU and GPU makers. For example a memory manufacturer will sell you 3333 speed DDR4 memory. This is the manufacturers guaranteed overclock minimum if the CPU and motherboard will support that speed. The DDR4 specification is that upper specification speed is 2133, so anything above that is overclocking. But even if the manufacture has listed the memory as 3333 speed there is a possibility that you will be able to push it to 3400. So with memory you may be able to get more than what is on the box.

For the CPU getting only the rated speed can be emotionally devastating. Right now reviews are regularly stating that they have no problem getting the i7-6700K to 4.5 GHz for a 12.5% speed increase. On sites that try to track overclocking achievements they have listed systems that have been verified as hitting 5.0 GHz for a 25% speed increase. The difference between them are mostly the "Overclocking Lottery". The Overclocking Lottery refers to the fact that for any specific chip you do not know how far you can push it before it becomes unstable till you try. With this anecdotal evidence there is a good chance that you will be able to get more than the speed on the package.

Graphics card are very much like memory in that the manufacturer designs, builds and tests overclocked cards. So you will have a supported overclock speed on the packaging. But because of the Overclocking Lottery many of the graphics card manufacturers do allow for you to see if your specific card will go even faster.

How Do I Plan For Overclocking?

1 - Read up on how to overclock the item

This is your chance to look up and take notes on what limits you should not exceed. This is one of the most important things to do to prevent breaking things.

This is also the time to learn recommended techniques to make adjustments to get the most out of the system.

2 - Get good software to measure system stability

Being able to boot Microsoft Windows is a start, but is your system stable when under load. There are several recommended ways to stress the system and verify that even under load that it will work properly and not glitch what you are doing or save bad data to your drives. Read the recommendations and choose one that you are comfortable with.

3 - Get a motherboard that "likes" being overclocked

What I mean by this is that not only do you want a motherboard that allows for overclocking you also want one that makes the entire process easy. You want one that is easy to get back to a state where the system boots if you go too far and the system will not boot. You want one that makes it easy to try each configuration. If each step is easy you are less likely to be frustrated and make too big of steps and have to undo your settings.

4 - Cooling

First off you want a case configuration that allows for more than enough airflow through the system. It is a little hard to keep your overclocked components cool enough to last a long time if there is not enough airflow and the inside of the case heats up.

Second you want to decide what type of cooling that you want to use with each item that you are overclocking and then make sure that it will fit in your case.

5 - Power

To have a stable overclock you really need stable power. At factory speed settings the components will be stable with a fair amount of fluctuation in voltage and amperage. As you overclock the amount of fluctuation that the components can handle and still be stable will decrease.

First off read up on the motherboard and the quality of the voltage regulators. Most reputable boards will use high quality components and they will have been reviewed multiple times. This will give you a good idea about how good the components on the motherboard are.

Second get a good power supply and one that is large enough. There is a correlation between power supply efficiency and the stability of the voltage and amperage. The better the efficiency rating the more stable the power is. But you also want to get a power supply with excess power available. As power supplies reach their design limit the stability of the voltage and amperage decrease. The more stable the power you put into the motherboard voltage regulators the more stable the power going into your components. Generally I try to have the actual used power be 15 to 30 percent below the power supply rating. I may even go higher if I plan to add several disk drives and other peripherals so that I do not need to plan on a new power supply when I do that.

In Conclusion

If you are willing to plan and put some effort into it you can safely overclock systems and often you will get a measurable improvement in performance.

As I explore each component of the build I will include some discussion about overclocking considerations if they apply. I also plan on revisiting the actual work to overclock in a later post.

Next in the series: Choosing a Case

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