This article was published in the September 2015 issue of Maximum PC. For more trusted reviews and feature stories, subscribe here.
The hardware, software, and know-how you need to get the most from your PC
Overclocking. It's long been a part of a PC enthusiast's toolkit when it comes to wringing every last ounce of power from our beloved machines. Whether you've opted to run AMD or Intel, overclocking has been a staple food group of the techie's diet for as long as there have been chips in PCs. The basic principle is very simple: Add more voltage to the component part, provide it with sufficient cooling, either through water or air (or Ln2 for the more adventurous among us), and increase the Hz output of the hardware you're trying to improve.
But this doesn't come without risk. While we've come a long way in the world of overclocking, it is still possible to fry your CPU, GPU, RAM, or motherboard to the point where it's more charred than your old man's best barbecued sausages. So, the first question you should always be asking yourself is whether it's worth the risk. The answer, generally (and, ahem, unhelpfully), is sort of.
As proven time and again by Intel's latest and greatest chips, a good-quality CPU core often outstrips an increase in gigahertz. on the flip side, however, increasing the performance of a two-year-old core so that it can keep pace with the newer generation can save you a pretty penny, and possibly put off that upgrade for another year or more. So read on for step-by-step guides to overclocking your CPU, RAM, and GPU.
Overclocking Your CPU
Learn to fulfill your processor's potential in 10 simple steps
Before crossing the start line, there are a few basic principles to get your head around. The first one is heat. Inevitably, the more voltage you add to your components, the more heat that component is going to output. Second, the higher the clock speed you're trying to achieve, the more voltage you will need to power that attempt. And third, there's only so much voltage your PC part can take before you start to see detrimental eff ects. These could be a drop in frame rates for GPUs, corrupting processes on the CPU, or even a failure to boot at all. These, essentially, are the basic limits of overclocking.
All chips are born equal, but some are more equal than others. You'll often hear overclockers talk of "The Silicon Lottery." In short, this is to do with the manufacturing process with each and every processor. Small imperfections in the application of the silicon lead to a variance in how well the chips perform, both in stability with an increase in voltage, and how much heat they produce at max load. You might get lucky with yours, or you might not. It can equate from anywhere between 0.2GHz difference to, in some cases, up to 1GHz in overclocking potential.
So, assuming you've got an aftermarket cooler of some description (see "Picking a Cooler," on page 46), that you have a processor or component that's capable of overclocking (K/X series for Intel and any AMD chip), and that you understand how to get into your BIOS, here's how to get going.
1. Checking CPU Stability
To ensure a successful overclock, we'll need to know that the CPU is stable at both idle and max load. To do this, we'll be using a free piece of software that's called Prime95, from http://bit.ly/1kVNJZh. You'll also want to download a program to accurately monitor the temperatures your CPU is outputting. For this, we'll use Core Temp, from www.alcpu.com/CoreTemp/, as this works with both AMD and Intel cores. There are alternatives out there—Corsair and NZXT have proprietary software that works with their AIOs, plus most motherboards have viewable temperature controls that you can use from the desktop. If you don't want to install anything on your rig, then Real Temp GT is your guy.
2. Core Temp
Once those programs are extracted or installed, load Core Temp to begin monitoring your CPU's temperature. Always look at the lowest core temperature to give yourself a good understanding of how hot your CPU is running.
3. Stress Tests
Now we'll want to benchmark your CPU, at stock, to see how hot it runs at 100 percent. Start Prime95, select "Just stress testing," and then you'll be given a list of options as to which stress test you'd like to perform. Choose "Blend Test" and press "OK."
Prime95 is a key overclocking tool, with its stress tests being a major part of the process.
4. Into the BIOS
After about 5–10 minutes, once your temperatures have stabilized, go into Prime95. Select "Test" on the top bar and hit "Stop," then restart your PC and mash that Delete key to get into your BIOS. In this test, we're using an ASRock Z97 Extreme 4 motherboard, so the UEFI could be a little different in comparison to some of the other manufacturers you'll find out there, but the base settings will essentially be the same.
5. Auto-Overclock
Once inside your BIOS, find the overclocking tab. In ours, it's named "OC Tweaker." Once in, you have several options. The easiest way to overclock your CPU is to let the motherboard do the majority of the work. Most manufacturers will include overclock profiles, usually ranging from 4GHz to 4.8GHz, depending on the CPU installed.
Setting the motherboard to run one of these profiles will allow it to attempt to overclock the chip to that frequency without any user input. This can be a quick solution, especially if you're only dialing in a conservative overclock (3.5GHz to 4GHz, for example), but this isn't conducive if you want to push beyond that 4.8GHz barrier, or if you can't reach that frequency through the automated profiles.
Default profiles limit potential, but are often safer than manually entering them.
6. Changing the Multiplier
More adept users will find manual control a lot more comprehensive in regard to what true overclocking is all about. To keep it simple, you want to be changing the CPU ratio, or multiplier, for all cores to the target number you wish to achieve. That's 35 in this case. The multiplier then works with the cores' BCLK frequency (usually 100) to create that final figure of 3.5GHz. In this tutorial, we're going to attempt to overclock our CPU, just to start with, from 3.5GHz to 4GHz, simply by changing the multiplier.
7. Test at Maximum Load
Once you've changed the CPU ratio multiplier to 40, save changes and exit the BIOS. Boot into Windows, open Core Temp to monitor your CPU temperature, then open Prime95 and select "Options," "Torture Test," then "Blends Test," to see how your chip fairs at maximum load. If it's stable for at least five minutes, we can then begin to up the multiplier to try to achieve a higher overclock.
8. Finding the Limit
At this point, you'll want to increase the multiplier by one and repeat the process of stress testing in Windows each time, until you reach the point where you initially either blue screen or your CPU begins to thermally throttle itself. Ideally, you want to blue screen before you reach your thermal limit.
9. Increasing the Voltage
To overcome the blue screen issue, we need to start working with the Vcore voltage. Back in the BIOS, you want to find CPU Vcore Voltage Mode. Change this to "Fixed." At this point, you may need to do some research as to what stock Vcore level your CPU takes, and what people are suggesting for overclocking. You'll want to begin increasing the voltage by 0.01 volts each time, until you can successfully boot, stress test, and maintain stability at your target frequency. Once you get a little more comfortable overclocking, you'll find yourself increasing voltages by 0.05 or 0.1 at a time. It's more about learning how your CPU responds to different amounts of voltage at this point.
Eventually, you'll reach a point where you cannot reach that next frequency, regardless of how much voltage you throw at it. This is when you want to dial back your overclock by 0.1GHz and drop the Vcore voltage back to the last stable settings for that frequency and maintain it there, as this is your final overclock.
Welcome to the blue screen of death. It's time to start playing with the voltage.
10. Back to Benchmarks
To ensure a stable overclock, you should now benchmark using Prime95 and CoreTemp for as long as you feel is appropriate. This can be anywhere from an hour to a full day, depending on how patient you are.
Picking a Cooler
The first thing to consider after you've decided on overclocking is what you'll use to cool your components. To put it bluntly, the stock coolers that AMD and Intel provide simply won't cut it when it comes to dissipating the excess heat that comes from adding more voltage. They're designed to deal with what the processor can output at stock frequencies, and not a lot more.
Air
The more traditional, easier solution would be to rely on air cooling for your CPU. There's a huge list of air coolers out there, but it's vital that you consider the size of the cooler versus the height of your RAM and the size of your case. The last thing you want is to buy a new heatsink for your shiny new i7-4790K, only to discover it won't fit over the top of your Corsair Dominator GTs. The Dark Rock Pro 3 is a particular favorite of ours—it's silent, yet can relieve your CPU of over 250W of TDP, plus it'll keep your bacon cool.
AIO Water Cooling
The second option, and one we all prefer here at Maximum PC, is an all-in-one water-cooling loop. You've probably seen a lot of these kicking about, Corsair's Hydro H100i being the more famous of the bunch. These are a quick and easy solution, and often provide a great deal more cooling than a single air cooler, due to their increased surface area. They're also a lot less tricky to install (providing you have the radiator support), and can clean up your rig quite nicely while allowing you to swap out components with relative ease.
Custom-Loop Cooling
Finally, the fully custom loop. It's the dream, the crème de la crème, and the aspiration of every tech enthusiast starting out on the bumpy road to a successful overclock. It's also something that's become increasingly easy to build in recent years. Although certainly the most effective of the three, due to the ability to expand on your loop by adding more radiators, and cool more components, it can become very rigid, especially if you want to change out a graphics card, for example. It's definitely something that needs to be researched fully before committing to, if only because it can easily add up to $500 to your costs. And that's without the real premium components. But wow, does it look good when you're done. The Parvum Titanfall rig is a prime example of this.
Mobos and PSUs
Once you've got your cooling sorted out, you'll want to make sure you've got the best possible components that you can budget for in regard to stability. That means two items in particular—the power supply unit (PSU) and the motherboard. They are both imperatively important when it comes to overclocking. Perhaps most obvious is buying a motherboard that supports overclocking. For Intel, that's any motherboard with the Z97 chipset. For AMD users, it's currently any FM2 or AM3+ board.
Concerning power supplies, you want to be looking at a PSU that has at least 20 percent spare capacity, in terms of wattage, over what your system requires. Preferably, push as much money as you can into it. The higher-end power supplies not only feature better surge protection, but also provide a more consistent flow of electricity between the wall and your PC parts. This should result in longer life and more stability, both when overclocking and through everyday usage.
Overclocking Your RAM
Wait! There's more! Overclocking isn't limited to just your processor
Yes. It's true. Overclocking doesn't just mean tinkering with your CPU. Other avenues exist if you're keen to shove the boat out a little bit more.
RAM speeds over the course of the last few years have almost tripled in frequency, meaning performance can be improved quite dramatically in certain computational programs. It's important to bear in mind, however, that the higher you push your RAM frequency, the more your CPU will suffer. In other words, it might mean an overall lower final overclock for your little powerhouse.
On the other hand, AMD's APUs, despite being a lower-end graphics solution, will benefit hugely from an increase in those same frequencies. So, what does all this come down to?
1. What's the Frequency?
Identifying the frequency of your RAM on purchase is crucial. We wouldn't go for anything less than 1,600MHz as a minimum if building a rig today. With Skylake and DDR4 around the corner, we'd be tempted to hold off a little and wait for that, as the price of the next generation of memory is still continuing to plummet.
Motherboard support may vary here.
2. The Profile Setup
We're using a pair of Corsair Dominator Platinums, clocked at a stock speed of 2,133MHz. To take advantage Pushing your CPU and RAM to the max. of any potential additional clock speed, you'll need to set up the memory with the correct profile on install. So, either Intel's XMP profiles or AMD's AMP profiles. This is exactly what we'll be using, just to do a slight overclock of the memory.
3. Upping the Frequency
Enter your BIOS by again headbutting the Delete key. Make sure you have either your XMP profi le or your AMP profile selected, then change the memory frequency to one frequency higher than your memory's stock frequency. In all likelihood, your RAM should be able to manage and maintain that frequency, regardless of what the stock speeds say.
Pushing your CPU and RAM to the max.
4. Above and Beyond
If you want to take it further, this time we'll change the BCLK frequency, instead of adjusting a RAM multiplier. You can up this in very small increments. But it also ups your CPU's basic overclock, so if you've already OCed your chip to the absolute max, it's unlikely you'll be able to push the memory or the CPU any further.
Overclocking Your GPU
Last, but certainly not least, the final hurrah of overclocking
With DirectX 11, at least, OCing the GPU is the area of most benefit to gamers. But it's also where overclocking has most dramatically changed. That's because, with Nvidia's GPU Boost and AMD's Power Tune, it's no longer possible to simply up the voltage and in turn increase cards' core clock speeds.
It's now often better to ignore the voltage and let the proprietary software do its own thing. This way, you can avoid reaching the artificial power limits set by our GPU overlords—cores won't throttle themselves in an attempt to control imaginary temperatures, that may or may not be present, even if they're running on an aftermarket cooler, or water.
Sounds ridiculous, right? You're not wrong. Still, we'll show you how far you can go with these cards.
1. Get the Software
Unlike CPU overclocking, we need to download some proprietary software to use within Windows to overclock our cards. It's usually most beneficial to download whichever manufacturer's software your card's PCB is based upon. GPU Tweak for Asus, Afterburner for MSI, Precision for EVGA, and so on. In this case, we're using a reference cooler on our GTX 980, so we're using MSI's Afterburner, as it provides us with frame monitoring for benchmarking, a customizable display, and in-game overlays to monitor how well these cards perform in comparison to their stock speeds.
2. Enable Monitoring
Once Afterburner is installed, the first thing we want to do is enable ingame overlay, and frame rate monitoring, followed by (for us at least) changing the skin to something a little more workable.
Afterburner's in-game overlay makes it easy to monitor how your GPU is doing.
3. Test Stock Speeds
Next, you'll want to get a clear understanding of how your card performs at stock speeds. We're using Total War: Rome II's benchmarking software, at maximum settings, at 2560x1440. We achieved a minimum frame rate of 19, a maximum of 61, and, more importantly, an average of 44.7.
4. Increase the Power Limit
With the benchmarks and stock speeds out of the way, it's now time to get into the overclocking side of things. Head back to the desktop and open MSI Afterburner again. The first thing we're going to increase is the power limit. Move the slider to as high as it will go (usually 110 percent). This should allow our card to use absolutely every inch of power we can get, beyond Nvidia's recommended stock settings, meaning the card can run all the way up to 91 degrees Celsius, as opposed to the stock 79 C.
5. Up the Clock Speed
Start by increasing the clock speed. Research what's most suitable for your card. In our case, a healthy overclock for the core clock should be an extra 225–275MHz offset, so we go for 240MHz.
6. Now, the Memory Clock Speed
Lastly, we're going to increase on average, is aiming for around 450MHz. We'll try that and see how it goes, leaving Nvidia's GPU Boost to calculate exactly how much voltage we need for everything. All that's left to do is press "Apply" and go back into the benchmark to see how well the card now performs.
Remember, if something goes wrong, a quick reboot of the system will reset all of your overclock settings to default.
In the Total War: Rome II benchmark, we achieved a minimum frame rate of 17 at overclock, a maximum of 67, and, more importantly, an average of 53.6. That's an increase of almost 9fps for the average. Granted, the delta between the minimum and the average is considerably greater than the stockclocked version, but who can argue with free performance?
| CPU Benchmarks | | | | |
| Core i5-4670k Turbo to 3.8Ghz | Core i5-4670k OC to 4.5Ghz | Core i7-4790k Turbo to 4.4Ghz | Core i7-4790k OC to 4.8Ghz |
| Idle Temp (°C) | 29 | 29 | 27 | 31 |
Load Temp (°C)
| 71 | 84 | 62 | 70 |
| Cinebench | 566 | 667 | 877 | 943 |
| Total War: Rome II (min/avg/max fps) | 19/40/59 | 16/40/53 | 16/42/58 | 17/42/57 |
| Vcore | N/A | 1.385 | N/A | 1.445 |
Tests carried out on max settings/shader model 4.1/1440p.
| GPU Benchmarks | | |
| Stockclocked GTX 980
| Overclocked GTX 980 |
Total War: Rome II
Minimum fps
| 17 | 17 |
Total War: Rome II
Average fps
| 45
| 54 |
Total War: Rome II
Maximum fps
| 57 | 67 |
3D Mark Firestrike
Extreme
| 5,654 | 6,558 |
Tests carried out on max settings/shader model 4.1/1440p.
| Test Bench Specifications | |
| CPU | Intel i5-4670K / Intel i7-4790K |
| Motherboard | ASRock Z97 Extreme4 |
| Memory | Corsair Dominator Platinum (2x 4GB) 2,133MHz |
Graphics
| Nvidia Geforce GTX 980 |
| SSD | OCZ Arc 100 (240GB) |
| Power Supply | BitFenix Fury 750W |
Conclusion
Welcome to the world of overclocking, a place where dreams are realized, and where having just enough of those overclocking chops may mean the difference between a world record–breaking benchmark and a night of crying into a pile of burned-out chips and GPUs.
As mentioned at the beginning of this guide, OCing isn't for the faint-hearted. You can do a considerable amount of damage to your CPU and other component parts, so it's not something to be taken lightly. What's more, in some cases, the performance gains are negligible. But, if you're interested in eking every last ounce of power from your machine, this is definitely the hobby for you.
It's something the vast majority of PC users will shy away from, and it's understandable why—the thought of placing extra strain on any of your components for the sake of a few more points in Cinebench hardly seems worth it at times. But when you're sitting there, in front of a stable 5GHz overclock on an ITX motherboard, with a chip being cooled by a single 120mm rad outperforming cores half its age, there's an odd sense of pride about it all. A bond between man and chip. Yes, we went there.
