Intel Core i7-8700K: Overclocking, Cooling & Temperature
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Overclocking, Cooling & Temperature
Overclocking
First, we established the Core i7-8700K’s limits by cooling the chip’s IHS to a constant 20°C, side-stepping potential thermal bottlenecks imposed by Intel’s unfortunate use of thermal paste between the die and heat spreader. We made it all the way to 5.0 GHz without any problems. This didn’t surprise us, given our experiences with Kaby Lake. At 5.1 GHz, we booted into Windows and ran a couple of games, but the processor called it quits when we tried to run Cinebench.
We’d like to point out the possibilities enabled by manual load-line calibration. Depending on the motherboard, different levels and presets are available, or the voltages can be manually adjusted for some experimentation. In this way, the core voltage can be reduced significantly without losing a whole lot of performance (so long as your chip plays along). For the motherboard we tested, the effective voltage was between 1.18V and a maximum of 1.28V when running Prime95 at stock frequencies. This lowered the package’s temperature by almost 8°C.
Unfortunately, many memory kits run into trouble if the load-line calibration is set too low; the result is general instability. CPU quality plays a key role as well. In our particular case, this affected our 5.0 GHz overclock, which didn’t hold up over time. All of the games and some of the workstation applications ran for hours without any problems, but Creo 3.0 and some of the HPC tests crashed after a few minutes.
The 5+ GHz overclocking stories are exciting, to be sure. But remember that most of them aren’t validated for long-term reliability.
We’d rather drop the clock rate by 100 MHz and not have to deal with intermittent crashes.
- Intel Core i7-8700K (Intel Core i7) at Amazon for $330
Looking at our power consumption and performance graph, we see a bend at ~4.8 GHz. Power use continues increasing with higher clock rates, but the Cinebench score levels off. A failure to continue scaling at 5.0 GHz is a good indicator that our CPU is throttling. It simply cannot dissipate heat quickly enough.
Power Consumption
At idle, the differences in power consumption are fairly marginal. All of the processors end up just about where we’d expect based on previous reviews. AMD’s Ryzen processors draw significantly more power than the Intel competition because their idle clock rate is a bit too high.
The new Intel CPU’s average power consumption in applications that combine 2D and 3D loads (like AutoCAD) is in line with the performance we observed.
The processor ends up in almost the same place during our gaming loop.
The finishing order changes dramatically once we fire up an AVX stress test with all cores running at their top Turbo Boost bins. During rendering, we were seeing the -8700K’s stock power consumption at 110W, climbing to 133W under a 5 GHz overclock.
AVX without offset pushes the result as high as 170W. The Core i7-8700K at 4.9 GHz even throttles due to its package temperature. And that’s in spite of our compressor cooler’s efforts! Thermal paste under the IHS does us no favors.
Temperatures
Here’s the good news: unless you render or run Prime95 for hours on end, a good air cooler can theoretically handle 4.8 GHz in a well-ventilated case. Intel’s thermal interface material isn’t desirable, but it shouldn’t stop you from achieving a decent overclock.
The above graph shows that a closed-loop liquid cooler is able to keep an overclocked Core i7-8700K from throttling after 20 minutes of warming up. A good heat sink and fan combination should perform almost as well, again, given ample airflow.
Under our stress test, the overclocked processor gets uncomfortably hot, even under our compressor cooler.
While we’re only measuring an average of 170W, thermal throttling keeps the 180W+ peaks from becoming our average power consumption result. At that point, even the most powerful coolers have to throw in the towel.
To be sure, it’s surprising just how much power such a tiny processor can consume once it’s pushed to its limits. Nevertheless, Intel’s Core i7-8700K is relatively easy to cool, even on air. You’ll just want to stay away from taxing rendering sessions and AVX-optimized workloads. At that point, you’re best off with an all-in-one closed-loop liquid cooler.
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i7–8700K overclocking. In this post I share my experience with… | by Artem Trunov
In this post I share my experience with overclocking a popular Intel i7–8700k processor from Intel’s so called 8th generation aka Coffee Lake. Besides being a first 6-core consumer CPU from Intel, it has some process improvements which makes it suitable for overclocking.
Intel’s z370 chipset comes to assist.
Update 1: With 5.1 GHz, I have onces managed to freeze a system under heavy DL load, so reduced to 5.0
Update 2: Since this post attracts a steady influx of visitors, I decided to list all my BIOS settings for your reference — see at the end of the post.
i-8700k die (Wikichip.org)
My first OC’ed system was Pentium 120. CPU frequency multiplier had to be set manually with a combination of jumpers on the mainboard. I bought a Gigabyte motherboard, then asked my more experienced colleagues their opinion on the brand. “Just a usual Taiwanese noname, man! You gambled, hope you are a lucky one!” Nobody new it in 1996. I have set jumpers to 120 and started it even w/o a CPU fan, just for testing. It worked, but I screamed when touched the CPU — it was so hot. I have then set jumper caps to overclock to 150 — worked. No multiplier lock was invented back then.
My second OC’ed CPU was Celeron 300A in a Slot1 form-factor.
This was the first introduction of the Celeron line. Intel differentiated it from Pentium line by lower FSB — 100 vs. 133 for Pentium II and III. However the Celerons had larger cache. One setting in BIOS could change FSB to 133 and 300A would become Pentium II 450 instantly. In fact, a bit superior because of the larger cache. The board was an iconic Abit-BH6 which served me almost 10 years due to unique upgradeability potential of the Intel platform back then. It supported Celeron 1400 as its max with just a BIOS update and a Slot1 adapter. Which was almost 5 times the CPU it originally supported! The RAM maxed out at 768 MB.
Nowadays I’d say, overclocking is a mixture of art and science, as there are so many knobs to turn, that it’s only possible to do something using lengthy trial-and-error method.
Also, you may or may not be able to repeat some one else’s success, depending on your particular chip — some may be less overclockable then others. This is called “silicon lottery”.
I was choosing between Rysen 2700X and 8700K, but eventually the deciding factor was built-in graphics of Intel’s chip. Since I only wanted to use a graphics card for Machine Learning, I assumed I should not share it with a display graphics. I’d probably have to buy an extra one, if I had Rysen. Ok, AMD will surely have my money when I shop for a headless devbox.
I have then picked a rather inexpensive 64Gb 3200MHz set from GSkill and got an Asus Prime Z370-A motherboard listed on the memory QVL. The board had a rare set of 3 16x PCIe slots, since most of boards I checked out only had two 16x slots, with the rest being 1x slots. I wanted to have an option to stick in 2 graphics cards and add my Intel PCIe storage card that I bough a while ago. Such configuration would run with 8+4+4 processor PCIe lanes respectively. If I trade my Intel PCIe storage card for a NVMe SSD that can use the chipset’s lanes, my remaining two cards could use 8+8 CPU lanes. A single graphics card could use full 16 CPU lanes.
I added a Super Flower Ledex II 750 Watts power supply, Alphacool Eisbaer LT240 all-in-one water cooler, and a spacious Fractal Design S case.
Intel’s turbo mode is remarkable.
source: wikichip.org
One can see that that the boost to only 4300 is guaranteed when using all 6 cores. We however will aim at 5,000 MHz max-turbo mode for all cores, even though not all chips are capable of that speed, according to statistics.
source: wikichip.org
I have delidded the CPU right after making sure it works. This is not such a big deal, and anyone who could put a PC together from parts should definitely be able to perform this delicate operation, given the right tools at hands. I have put Grizzly Conductonaut between the CPU die and the inner surface of the lid.
I have settled on Intel’s LINPACK as a torture tool with occasional use of prime95. These are very well written pieces of software and they impose a lot of load on the system via use of AVX/AVX2 instruction sets.
The tools are pretty good at pushing the system to its limits and finding instabilities. If your system does not hang, reboot or produce math errors during these tests, you are assured trouble-free execution of whatever apps you have.
I have also put together a 30 minute test of some numpy and sklearn functions resembling typical Machine Learning workflow.
On the monitoring side, I used PCM, turbostat and i7z. Cudos for the latter for being able to show core voltage.
Full review on the Linux overclocker’s toolbox is in another post: Over-clocking under Linux
I also used a wall socket power meter as objective measure of power consumed by the system.
LINPACK and prime95 are pretty resource demanding, but do you really want to solve systems of tens of thousands linear equations on your desktop all day long? The answer is, of course, depending what you do on your desktop besides typical web browsing. Video editing? Perhaps, you need to test video encoding software.
Gaming? Then use gaming benchmarks.
I’d like to do Data Science. I found typical Machine Learning code from Python’s sklearn not too tasking. Even Xgboost and LightGBM, that use openmp to run on all available CPUs use AVX family instructions scarily, leading to rather cool temperatures.
So, in order to be able to measure impact of changing settings in my real life scenarios, I have put together a benchmark, that applies some common algorithms to synthetic (generated on the fly), but realistically looking data.
More on this benchmark and its results in my another post.
It turned out that it’s not that difficult to make my system running at 5GHz, but it was rather difficult to make it running stable under extreme load.
Intel’s stated TDP certainly not account for maximum load a processor can take, not even on the base advertised frequency. Want to prove it? Run LINPACK and see your power draw exceeding the stated TDP value, and possibly see your processor throttling under the base speed, if you don’t have adequate heat removal setup.
For this reason, MB vendors all have “AVX offset” in their BIOSes — it will drop CPU frequency multiplier by this offset, so the CPU runs cooler and can sustain the load.
Part of the problem was that MB vendors want to make overclokers’ life easier and make many options Auto, with some default settings and default behavior. Not only these settings may be unknown, and not optimal, but the logic behind some Auto algorithms is unknown or too power hangry. For this reason, experience overclockers advise to set the most critical options, such as Vcore voltage manually.
I have felt this on my own skin, when I discovered, that my system is heavily throttling the CPU with default (out of the box!) BIOS settings. Carlyle from Asus ROG Forum suggested that 64GB of RAM is too tasking for the system, and Asus algos want to support the memory controller with more voltage, which leads to overheating and thermal throttling. He suggested to remove some RAM and check if I’d still have throttling.
With 32GB I still observed throttling, while at 16GB everything was just fine! So I took it then, that since most gamers do not require more than 16GB of RAM, vendors also test with typical 2x8GB combos, and I am on my own with my 4x16GB. On another thought, Intel memory controller still has some blame too, since it’s true indeed, that only small amounts of RAM can be overclocked to extreme (4+ GHz) speeds on a current Intel platform. Also, remember Mac users’ uproar about Macbook’s 16GB RAM limit a while ago? This must be the same story — large RAM would eat disproportionately more power.
For the same RAM reasons, I suppose, recipes from der8auer and The Sentinel failed on me — the system was not stable or was throttling under LINPACK load.
Asus EZtune, 5G profile from the BIOS, recipes from der8auer and The Sentinel failed on me — the system was not stable or was throttling under LINPACK load. The settings were just too aggressive. So I had to fully understand what’s going on.
It’s important to understand, that setting up voltages (Vcore, VCCIO, System Agent) is not enough — they are not stable and drop under load. They can be supported by LLC — Load Line Calibration, that can compensate more or less aggressively (level 1–7). Undervoltage leads to system instability, overvoltage leads to overheating, throttling and instabilities as well.
Thus, you are optimizing a target max-turbo frequency, Vcore, VCCIO, VCSA, and LLC.
One would set them up in Vcore manual mode, trying to minimize LLC level and vcore to make system that is stable at the minimal power consumption.
Then some folks also overclock RAM, but I settled down on my stock XMP profile. Aiming at higher than 3200MHz speeds would unlikely get a lot of performance for 64GB kit.
Finally, there is an option to overclock cache (or uncore) speed, but I just left these setting all at auto. I have to admit I didn’t want to spend to much time on overclocking. While it’s fun, there is always some work to do.
I have settled down on Adaptive vcore mode, that lets SVID to adjust the voltage, and then one can configure some offset to the resulting vcore. I also let some moderate LLC levels to help boost VCCIO and VCSA in case of load, since too high voltage and higher current would definitely lead to overheating.
It’s important to note, that higher voltages and frequencies do not lead to extra power consumption in the absence of load! My system has idle power consumption about 30Watts (at wall socket), while it consumes 75 Watts during single core load (other cores are in C1(HALT) or deeper states), and could reach 110 W with Logistic Regression, 160 W with LightGBM and XGBoost, and 260 W or more under LINPACK (unstable at 5HGz though).
I could run the usual ML workflows and even prime95 at 5GZ with no AVX offset, but I could not run LINPACK at 5GHz. LINPACK was stable at 4.8 GHz (AVX offset 2), and even then would sometimes produce few LINPACK errors, making a test failed. XGBoost, LightGBM could happily run at 5.
1 GHZ, all not too hot.
If I leave the AXV offset at 2, I surely loose some of numeric performance, since AVX is indeed used here and there across numpy, so my CPU would have to switch back and force between frequency states, and this is not so good — it will also put a core into HALT states briefly.
I have decided to leave the settings at 5.0 GHz with no AVX offset thinking that I’ll know what to do if I meet a real life app that would push my CPU to an instability zone.
AI Tweaker menu:
XMP Profile — DDR4–3200
BLCK Frequency — 100,0 (unchanged)
ASUS multicore enhancement — Disabled
SVID Behaviour — Best-Case Scenario
AVX Offset 0
CPU core ratio — Sync All Cores
1-core ratio limit — 50
BLCK Frequency DRAM Frequency Ratio — Auto
DRAMM odd Ratio Mode — Enabled
DRAM Frequency — DDR4–3200 MHz
TPU — Keep Current Setting
Power Saving & Performance Mode — Performance Mode
CPU SVID Support — Auto
Ai Tweaker\DIGI+VRM Submenu:
CPU LoadLine — Level 5
CPU Current Cap — 140%
<the rest are default: Auto>
Ai Tweaker\Internal CPU Power Management submenu:
Intel SpeedStep — Enabled
Turbo Mode — Enabled
Long Duration Package power limit — 130
Package Power Time Window — 1
Short Duration Package Power Limit — Auto
IA AC LoadLine — 0.
01
IA DC LoadLine — 0.01
CPU Core/Cache Current Limit Max — 255.50
CPU Core/cache Voltage — Adaptive Mode
- Offset Mode Sign — “-”
- Additional Turbo Mode CPU Core Voltage — 1,370
- Offset Voltage — Auto
DRAM Voltage — 1.3530
CPU VCCIO Voltage — 1.15000
CPU System Agent Voltage 1.17500
Advanced Menu:
HyperThreading — Disabled
Tcc offset time window — 5 sec.
This combination produces CPU core voltage 1.4 under load.
Wikichip article
de8bauer overclocking 8700K with ASUS MB
The Sentinel overclocking 8700K with ASUS MB
Kabylake overcloking guide from Asus guru
Tweaktown overclocking guide
BIOS settings guide (in Russian)
Intel Coffee Lake: Overclocking Core i7-8700K
We have already published a guide to overclocking Skylake and Kaby Lake processors, now it’s time for a new generation of Intel processors called Coffee Lake.
We will check how well the new Intel processors overclock, and how much gain can be obtained from the 14nm ++ process in terms of clock speeds. We took three Intel Core i7-8700K processors from retail. We will conduct overclocking tests, including tests after removing the heat spreader and replacing the TIM.
While six cores and 12 threads are new to Intel’s mainstream platform, many features remain the same. With the new generation, there is still a problem of chip quality variation, which experienced users are well aware of. We repeat for everyone else: even in one series, there can be a serious variation in the quality of chips, so they show different overclocking results. And it’s hard to come up with a general verdict. To improve the relevance of our tests, we tested three retail models of the Intel Core i7-8700K. It will be interesting to see if two extra cores make overclocking more difficult. We used the ASUS ROG Maximus X Apex motherboard, which is not only equipped with a powerful power supply subsystem, but is also well suited for overclocking, including extreme overclocking.
The board has numerous direct voltage measurement points, and there are also built-in buttons and toggle switches for various OC functions to facilitate working with the board in an open test bench.
We will re-add the overclocking results of our international forum users to make the article as useful as possible. Nevertheless, the corresponding forum topic already has more than 100 pages, where users share their overclocking results. It is no coincidence that among users the choice of a processor is called a lottery («Silicon Lottery»): depending on the generation, process optimizations within the generation, the quality of the crystals and other factors, each chip gives different overclocking results.
Heat spreader of the new Intel Core i7-8700K near
For Coffee Lake, the following remains true: there are separate batches or groups of processors (with a certain serial number) that are considered to be better overclockable.
Overclockers often look for processors of the right batches in stores, but there are no guarantees here either. Only overclocking tests can show how well a particular chip overclocks. In addition, in recent years, Intel processors have become more uniform in quality, so we should not expect significant differences. And judging by our observations, this trend continues with Coffee Lake.
Finally, as part of our article, we will remove the heat spreader from one of the processors, after which we will evaluate the effect of the new thermal interface TIM (Thermal Interface Material) on the results of CPU overclocking and temperature. Is such a risky procedure really justified?
For overclocking tests, we purchased three Intel Core i7-8700K processors with the following batch IDs:
- Intel i7 8700k #L729C231 #1
- Intel i7 8700k #L729C231 #2
- Intel i7 8700k #L729C229
We purchased three regular retail processors from different retailers.
<>Intel Coffee Lake: Overclocking Core i7-8700K
Overclocking and Voltage Basics
Intel Core i7-8700K Processor Review and Test: Six Cores Coffee Lake
Table of Contents
2 9022
- WinRAR
- XnView
- Adobe Photoshop CC 2017
- Cinebench R15
- Adobe Media Encoder CC 2017
- X265
- Adobe InDesign CC 2017
- Hexus pifast
- Corona 1.3. Benchmark
- SVPmark
- Geekbench 4
- HEVC
- Battlefield 1
- The Witcher 3: Wild Hunt
- Deus Ex Mankind Divided
- Total War Warhammer
Introduction
“2…4 = 4…6” — this is how one phrase can explain the whole essence of what is happening.
To improve its position in the market, Intel needed to increase the number of cores and raise the base frequency of the memory. And all new processors have got two additional cores and support for DDR4 2666 MHz memory.
The physical dimensions of the new CPUs have remained unchanged, and although the processor socket looks the same visually, some of the reserved pins are now used to supply voltage.
Everything is unchanged under the heat distribution cover — TIM as the main thermal interface. As before, for a good overclocking, the processors will have to be scalped. Fortunately, this is done easily and painlessly, since there are no protruding capacitors under the cover.
recommendations
However, it’s hard to explain the company’s desire to release a new chipset for a relatively old architecture.
| System logic set |
Intel Z370 |
Intel Z270 |
| Intel Optane memory support |
V |
V |
| Intel Virtualization Technology for Directed I/O (VT-d) |
V |
V |
| Intel vPro Technology |
— |
— |
| Firmware revision Intel ME11 |
|
|
| Intel HD Audio Technology |
V |
V |
| Intel Rapid Storage Technology |
V |
V |
| Intel Rapid Storage Technology Enterprise |
— |
— |
| Intel Standard Manageability Technology |
— |
— |
| Intel Smart Response Technology |
— |
V |
| Intel Stable Image Platform Program (Intel SIPP) |
— |
— |
| Intel Rapid Storage Technology for PCI Storage Devices |
V |
V |
| Intel Smart Sound Technology |
V |
V |
| Intel Platform Trust Technology (Intel PTT) |
V |
V |
It’s easy to see that nothing new has appeared in the Intel Z370, except for support for the next generation of Optane Memory and the missing Intel Smart Response item.
As a result, users were presented with an updated platform with repurposed LGA 1151 pins and the need to purchase a new motherboard. Perhaps this is justified by the increase in productivity?
Specifications
| Model |
Basic frequency, GHz |
One core |
Two cores |
Three four cores |
Five six cores |
Seven eight cores |
Nine and more |
cores |
Number threads |
L1 cache, MB |
L2 cache, MB |
L3 cache, MB |
Maxi- small estimated power, W |
Recommended finished cost, $ |
| AMD Ryzen 7 1800X |
3.  6 |
4.1 |
4 |
3.7 |
3.7 |
3.6 |
— |
8 |
16 |
0.7 |
4 |
16 |
95 |
399 |
| AMD Ryzen 5 1600X |
3.6 |
4.  1 |
4 |
3.7 |
3.6 |
— |
— |
6 |
12 |
0.5 |
3 |
16 |
95 |
229 |
| Intel Core i7-8700K |
3.7 |
4.7 |
4.  6 |
4.4 |
4.3 |
— |
— |
6 |
12 |
0.3 |
1.5 |
12 |
95 |
359 |
| Intel Core i7-7740X |
4.3 |
4.5 |
4.5 |
4.  5 |
— |
— |
— |
4 |
8 |
0.2 |
1 |
8 |
112 |
339 |
| Intel Core i7-7700K |
4.2 |
4.5 |
4.4 |
4.4 |
— |
— |
— |
4 |
8 |
0.  2 |
1 |
8 |
91 |
339 |
| Intel Core i7-6700K |
4.0 |
4.2 |
4.2 |
— |
— |
— |
— |
4 |
8 |
0.2 |
1 |
8 |
91 |
339 |
Positioning
Overclocking
Let’s not bore the reader and start with the most interesting — overclocking the Intel Core i7-8700K.
As you already understood, Coffee Lake will not bring us anything new in this regard. The architecture has not changed, because only a couple of cores have been added. To power them, Intel used spare points in the socket and all previous CPU models became incompatible with the new processor socket.
The TDP level has increased from 91 to 95W, but if you choose a processor by this parameter, the i7-7740X looks more interesting with its 112W. It does not have protection at 94 ° C, which allows you to heat the crystal up to 100 ° C. And taking into account TIM under the cover, six degrees of difference allow you to overclock the i7-7740X to a higher frequency without scalping.
However, we were lucky, and under the lid of the test instance of Coffee Lake was the first fresh thermal paste. This is also confirmed by the heating results.
In terms of power consumption, the new processor overtakes all classmates.
Note that these are the results of the stand without a monitor.
The i7-8700K itself consumes up to 170 watts during overclocking. When operating at the nominal frequency, power consumption in tests with AVX instructions reached 110 watts.
As a result, the CPU frequency, at which 100% stability was maintained, became 4.5 GHz with zero offset for AVX and 4200 MHz for LLC.
With factory settings and a load on one core, the CPU frequency rises to 4.7 GHz and up to 4.4 GHz for LLC.
Under load, the processor frequency drops to 4.3 GHz, the LLC frequency decreases proportionally to 4.0 GHz.
To achieve higher frequencies during overclocking, it is necessary to select the AVX multiplier and reduce the LLC frequency. For example, for 5 GHz, after reducing the frequency for AVX tasks to 4.5 GHz, a voltage of 1.325 V was required.
The processor passed all tests, but in programs where AVX instructions were used and there was a pronounced dependence on the LLC frequency, the overall performance turned out to be lower than when overclocked to 4.
