Overclocking

UEFI #1

Assuming your system boots (big assumption!) and you're able to install your OS, you might want to try your hand at overclocking. We've assembled a series of UEFI screenshots (click on any to magnify) setting forth what you should be looking for to overclock a Kaby Lake-based processor (e.g., the Core i5-7600K or Core i7-7700K). To access the UEFI, tap the delete key during the boot sequence. You'll be greeted by a colorful screen like the one you see here, which is for the MSI Z270 Gaming Pro Carbon board we used. The first thing you'll want to do is enable your RAM's XMP profile, which in this UEFI is done simply by clicking a button in the upper-left. For other UEFI's you may have to hunt around a bit for it in the menu. Note that we strongly, and we do mean strongly, discourage you from attempting to manually overclock RAM beyond the XMP settings. In most cases, this will fail instantly, and in nearly every other case, it will appear to work but will cause random system bluescreens. In other words, it's not worth it!

OC

The next step is to enter the CPU overclocking menu. You'll want to engage the manual overclocking mode, called "Expert" here, but may be called "advanced" or "manual" in other UEFIs. What you'll see is that we've dialed in a 50x multiplier (which translates to 5GHz under load). Note that with any manual overclocking, the Turbo function is shut off, so the instant you enter in a custom multiplier, all the various Turbo levels are disabled. A Core i7-7700K operates at 4.4GHz under a quad-core load at stock settings due to its Turbo function, which means that 5GHz, as impressive as it sounds, is actually just a 14% overclock. Furthermore, to prevent overheating and to maintain the utmost stability, we entered in a -4 offset for AVX loads, which will reduce the operating clock speed to 4.6GHz in AVX tasks, including some benchmarking and stress-testing applications. As it turns out, our CPU was capable of sustaining 5GHz in AVX loads, but it pushed very high voltages and temperatures, so we're going to recommend that all but the most expert of tweakers use that helpful AVX offset.

Adaptive

Next you have to provide additional voltage. In our testing, the motherboard would automatically increase voltage to provide a stable overclock at 5GHz, but the voltage was actually too high, leading to extremely-high temperatures. Therefore, we recommend that you select "adaptive" mode (or the new adaptive + offset mode that's been added for Z270-based motherboards), and manually enter a voltage level. We chose 1.25V, which is pretty low for 5GHz, but it was stable in our testing. It actually translated to about 1.26V in Windows, as you'll see momentarily. Choosing adaptive rather than "fixed" or "override" will allow the voltage to back off at idle, which is great for reducing power usage and excess heat.

Fans

Before we save our UEFI overclock and restart the system, we want to enter the UEFI's Hardware Monitor to dial in some custom fan profiles. By default, motherboards will often run case and CPU fans close to full speed, but an expert builder should customize these to allow for low fan speeds at low temperatures, and maximum fan speeds under extreme stress. Our unique Arctic Freezer i32 CPU Cooler can actually properly run at zero RPM (most fans may buzz or throw a UEFI error if set to 0). We take advantage of that feature here by having the fan only start spinning at 55 °C. By 85 °C, it will be at 100%. You can go through each one of your case fans and do something similar, but we suggest you start at 40% (or alternatively around 600RPM) to avoid the fan buzzing due to inadequate voltage. Many case fans will not operate properly below this level.

OK, once we save our settings and restart, we'll hopefully arrive at the Windows desktop - if we don't, we may have to tweak our overclock and voltage settings. Luckily, we didn't run into any trouble, so can go ahead and run a few benchmarks to see how this overclock is doing:

OC CPU-Z

Good news! Under the moderate load presented by the stress test built into the handy utility CPU-z, our system is humming along just fine at 5GHz. According to HWMonitor (another great utility by the same folks who created CPU-z), the CPU temperature doesn't exceed 73 °C, thanks in part to the moderate 1.256V running through the processor. We consider CPU-z a very good approximation of the load that typical applications will generate, including games. Unless you're doing serious video transcoding or other demanding work, you won't hit higher temperatures. But let's see how things go when we throw an AVX load at the system courtesy of Intel Burn Test.

AVX

Ah, nice and toasty! The CPU hit 83 °C, despite the fact that the CPU was operating at 4.6GHz, thanks to that useful -4 (i.e., -400 MHz) offset we selected in the UEFI. Here voltage exceeded 1.26V. Note that this is still in the safe zone, but the compact CPU cooler we used (the Arctic Freezer i32) is probably the minimum cooler you'd want to go with for serious Kaby Lake overclocking. Because the case we used only had about 160mm of clearance for CPU coolers (158mm according to the specs, but we measured a bit more than that), big 140mm-based tower coolers were out of the question. They'd stick right out the side of the case. This is something builders really have to be careful about when they try to mix and match coolers and cases. We always triple-check compatibility in our Do-it-Yourself PC Buyer's Guides, so that's a good resource to consult if you're looking for a matching setup.

In terms of GPU overclocking, things are actually quite a bit simpler, for better or for worse. As it happens, with the current generation of Pascal-based GPUs, there's really very little to overclocking, both in terms of effort and reward. Every Pascal-based GPU we've tested (and we've tested over half a dozen) will hit between 2000MHz and 2100MHz, which translates to a 8-12% overclock. Just download MSI Afterburner (our favorite free utility by far) and start with a +150MHz offset above reference, and see how far you can push it.

Afterburner

Because our EVGA GeForce GTX 1070 SC 8GB card came pre-overclocked from the factory by about 90MHz, we added an additional 78MHz in MSI Afterburner, as shown in the screenshot here, to arrive at a total overclock of 167MHz. Depending on how you calculate it (versus base clocks, published boost, or actual in-game clockrates), this is about an 11% overclock. Most cards will start crashing before they get to +200MHz. In terms of VRAM overclocking, you can typically get between a +250MHz and a +500MHz offset (which due to the effect of double-data rate RAM translates to an overclock of 500MHz to 1000MHz). Our card was stable with a +496MHz memory offset, and we didn't push higher.

Dual GPUs

Final Thoughts

There's really nothing more rewarding than using your own two hands, a little patience, and a little ingenuity to build yourself an ultra-capable PC. We know that the thousands of readers around the world who have followed our guides over the past four years would probably agree, which is why we keep coming back and publishing guides like this one month after month and year after year!

And the great thing is you can choose your own price level, form factor, and combination of capabilities to fit your needs and your needs alone. Just because someone else has a hulking tower for a PC doesn't mean you have to! We specifically chose an ultra-compact ATX case because we think this form factor is kind of cool, even if it is just a bit limiting in terms of what can be crammed inside. By the way, all you eagle-eyed readers will notice that we made one final "adjustment" to our build, just for fun. Take a look inside our system's windowed side panel and check out what we managed to add to our build. Yes, it really works, no thermal issues whatsoever thanks to the excellent SilverStone RL06-Pro case!

We hope you've found this guide useful... perhaps it will even inspire you to build your next PC! As always, to see our latest recommendations on component picks in every price range, check out our Do-It-Yourself Buyer's Guides, updated on a monthly basis to keep you up to speed on all the latest developments.

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