Laptop Overclocking: 4.0GHz on i7-6820HK, 1200MHz on GTX 970M

By Published January 26, 2016 at 1:00 pm

The GTX 980's entry into laptops – without suffixed “M” demarcation – provided a look at the world of true desktop graphics as integrated on mobile devices. We reviewed MSI's GT72S Dominator Pro G ($2760) with its GTX 980, conducting additional overclocking tests to determine just how far the desktop part could be pushed when crammed into a laptop.

Turns out, it was pretty far. And we're revisiting the subject with Intel's new i7-6820HK and the GTX 970M. This benchmark looks at just how far a laptop CPU and GPU can be overclocked, then runs game FPS and Adobe tests to determine if OCing is worth it. We use The Witcher 3, DiRT, GTA V, Shadow of Mordor, and Metro for FPS tests, then run trace and automated testing for Photoshop and video editing software. A CyberPower Fangbook 4 SX7-300 was used for the benchmark, which is outfitted with the 6820HK unlocked CPU.

CyberPower Fangbook 4 SX7-300 Specs

Model Fangbook 4 SK-X17 Pro Gaming Laptop
CPU Intel Core i7-6820HK 2.7GHz Turbo 3.6GHz
8MB Cache, Unlocked
Motherboard Mobile CM236
SSD M.2 SATA 250GB Samsung 850 EVO
Optical 8x Ultra Slim DVDRW
Internal Wireless Card Intel Dual-Band AC3165
Bluetooth 4.2
Sound Dynaudio 7.1 SPDIF
2x 2W speakers
1x 3W sub-woofer
Keyboard RGB color-programmable
Media Devices Built-in SDXC/HC reader
Battery & AC Drop 9-cell Li-Ion
230W AC adapter
Webcam Built-in HD 30FPS webcam
USB 6x USB3.0
Warranty 1-year limited, lifetime technical support
Price $1885

The unit we're using for testing hosts an Intel i7-6820HK CPU, which is new in Intel's mobile lineup and allows for overclocking. Similar to desktop SKUs, the “K” signifier indicates that the CPU is “unlocked” – or that its multipliers can be changed. Our model is running 2x8GB (16GB total) of G.Skill memory (DDR4), an nVidia GTX 970M mobile GPU, and 250GB M.2 SSD. Other extras are defined above.

Battery life and build quality will be analyzed in future content. For today, we're sticking with pure overclocking benchmarks.

Test Methodology

Our laptop test methodology parallels what we employ in GPU reviews. Specifically for overclocking tests, we've added the use of PCMark 8 for trace-based and automated testing of production software, meant to aid in rooting-out differences between CPU and GPU clock-rates.

For games, we tested using Metro: Last Light's benchmark on very high & high (tessellation) settings, DiRT Rally on ultra (4xMSAA), The Witcher 3 on ultra (HairWorks off, SSAO, AA off), and GTA V on very high and ultra (where applicable) with no advanced graphics.

All FPS tests were performed three times for parity. FRAPS was used to log FPS data in 30-second increments, then that data was dissected with a spreadsheet. These tests were conducted with AC power connected.

Synthetic testing was performed using 3DMark for validation. Thermal data was logged during the 3DMark Firestrike Extreme GFX 2 test, stressing the GPU at 100% load for 24 cycles.

Battery life was not tested for this overclocking benchmark, as OCing on battery frankly does not make sense (and would be restricted, anyway).

As a reminder, our benchmark shows these items:

  • Average FPS: The time-averaged frames per second of gameplay.
  • 1% Low FPS: The FPS displayed 1% of the time. This is a better indicator than "minimum" because it is not an outlier and is more likely to jar the user.
  • 0.1% Low FPS: Same as above, except 0.1% of the time.

The latest nVidia drivers (361.43) were used on all systems. MSI Afterburner was used to overclock the GPU core clock and memory clock, with discussion on the procedure further down.

PCMark testing primarily looked at these items:

Video To Go part 2 - total_transcoding_time
Music To Go
Music To Go - total_transcoding_time
Video Editing part 1 v2
Video Editing part 2 v2
Adobe Photoshop light - open_photoshop_time
Adobe Photoshop light - process_image_01_time
Adobe Photoshop heavy
Adobe Photoshop heavy - open_document_time
Adobe Photoshop heavy - resize_image_time
Adobe Photoshop heavy - create_color_range_layer_time
Adobe Photoshop heavy - merge_layers_time
Adobe Photoshop heavy - apply_lens_blur_time
Adobe Photoshop heavy - edit_lens_blur_layer_time
Adobe Photoshop heavy - clear_gradient_time
Adobe Photoshop heavy - save_document_time
Adobe Photoshop heavy - export_to_tiff_time
Photo Editing v2 - load_image_matrix_time
Photo Editing v2 - adjusting_time
Batch Photo Editing v2 - batch_transforming_time
Batch Photo Editing v2 - loading_time
Batch Photo Editing v2

PCMark 8 tests for the above were conducted three times for parity, then averaged.

Note that comparing cross-platform systems is challenging. There is an inherent performance delta from the CPU change, primarily, and that's something we can control for with some careful planning. For the desktop machine, despite having Skylake processors on-hand, we opted to use an i7-4790K for its comparable clockrate to the high-end mobile i7 CPUs. Turbo Boost was disabled on the desktop for more linear results. All CPUs are 4C/8T.

A factory-overclocked GTX 980 cannot be used for these tests. We used a reference 980 for its more linear clock rates.

Games must be GPU-bound to avoid exaggerating the CPU difference. Our game benchmark section is more slimmed-down than for GPU reviews, but this is for careful methodology reasons – we had to eliminate anything that relied too heavily upon CPUs when performing GPU comparisons, especially cross-platform.

Desktop bench below:

GN Test Bench 2015 Name Courtesy Of Cost
Video Card

This is what we're testing!

Various -
CPU Intel i7-4790K CPU CyberPower
Memory 32GB 2133MHz HyperX Savage RAM Kingston Tech. $300
Motherboard Gigabyte Z97X Gaming G1 GamersNexus $285
Power Supply NZXT 1200W HALE90 V2 NZXT $300
SSD HyperX Predator PCI-e SSD Kingston Tech. TBD
Case Top Deck Tech Station GamersNexus $250
CPU Cooler Be Quiet! Dark Rock 3 Be Quiet! ~$60

Traces and automation were used for Photoshop benchmarking when comparing overclocked vs. non-overclocked components, and used to determine whether overclocking is worth it, can be found below. Batch photo editing, video editing, and other trace files are also below:

Methodology Automation – Batch Photo Editing

Batch Photo Editing Images File Sizes Resolution
Source Files 32 TIFF 4.7-52.3MB 2674x1506
Final Files 32 TIFF 6.3-66.7MB 2674x1506

Methodology Automation – Music Transcode

Music Transcode Files Target bit-rate
WAV 32 Source
AAC 32 Target

Methodology Automation – Video Transcode

Video Transcode Files Resolution Bitrate
Source video 5 1080p 25Mbps
Final video 1 5 720p 5MBps
Final video 2 5 1080p 8MBps

Methodology Automation – Adobe Photoshop Lightweight Benchmark

1. Start Photoshop.

2. Open a series of 14 images, one by one. For each, perform a series of operations:

a. Close the previous image if one is open.

b. Adjust color balance.

c. Apply auto levels.

d. Adjust shadows and highlights.

e. Downscale the image using bicubic interpolation.

f. Apply unsharp mask to the image.

g. Save the image into a new file.

3. Close the final image and exit Photoshop

Photoshop Light Images File Sizes Resolution
Source 14 3.9-17.6MB 2500x1677
Destination 14 388-778KB 1200x800

Methodology Automation – Adobe Photoshop Heavy Benchmark

1. Start Photoshop.

2. Open a PSD document.

3. Upscale the image using bicubic interpolation.

4. Change the color depth to 16 bits per channel.

5. Create a color range selection and paste it into a new layer.

6. Merge the two existing image layers and place the new layer topmost.

7. Apply lens blur to the topmost layer.

8. Select an elliptical area in the topmost layer and remove it.

9. Merge all existing layers into a new topmost layer.

10. Apply Gaussian blur to the topmost layer.

11. Select a gradient mask and remove the selection from the topmost layer.

12. Reduce the opacity of the topmost layer.

13. Save the image into a new PSD file.

14. Export the image into a new TIFF file.

15. Flatten the image and downscale it using bicubic interpolation.

16. Apply unsharp mask on the image.

17. Export the image into a new JPEG file.

18. Close the image and exit Photoshop.

Photoshop Heavy File Size Resolution DPI Layers
Source PSD 113MB 5184x7744 300DPI 1
Final PSD 1320MB 7000x10457 300DPI 4
Final TIFF 476MB 7000x10457 300DPI n/a
Final JPEG 177KB 1000x1494 300DPI n/a

See PCMark 8 for more.

Fangbook 4 – i7-6820HK & GTX 970M Overclocking Results

Notebooks don't presently provide voltage control for GPU overclocking, but nVidia has previously told us that this is a future consideration. We're able to use Afterburner or other GPU OC software to manipulate the core clock and memory clock. Clockrates are incremented gradually and benchmarked throughout the process to determine points of failure or instability.

Power % target modifications are not supported at this time. The GTX 970M runs at 100% TDP target at all times.

CPU overclocking is conducted through BIOS. We didn't push the laptop as hard as we might push desktop components given the generally lower tolerance for gains (we can't [easily] switch to a higher-end cooler for higher clocks, as can be done with liquid or dry ice on a desktop). The Fangbook 4 SX7-300 has a specific “OC” tab in BIOS, providing finer control over laptop overclocking than we're used to. Multipliers, voltages, and BCLK can all be tuned. For this benchmark, we only played with the multiplier and did not touch BCLK; that will be examined in more depth in future content. The goal for today was to see how far an “easy OC” could get us in benchmark performance.

Our overclocking tests are more transparent than most; we reveal the entire process of increments and decrements, hopefully aiding enthusiasts in their own OC attempts. Afterburner is used to gradually increase the CLK offsets for memory and the cores, with thermals constantly logged through GPU-Z and AIDA64.

We conducted a 3-minute pass for the initial test, just to find the trouble spots, then shifted to a 30-minute FireStrike looping endurance test once we found what we suspected to be the max clock-rate. CPU overclocking was tested with the physics test. GPU overclocking was tested with the GFX 2 test.

CPU OC - Fangbook 4 - i7-6820HK
Multiplier Clockrate Voltage Initial Test Endurance
27 2.7GHz 1.12 P  
33 3.3GHz 1.16 P  
37 3.7GHz 2.01 P  
40 4.0GHz 2.3 P P
42 4.2GHz ? Kernel failure  

GPU overclocking:

GPU OC - Fangbook 4 - GTX 970M
CLK Offset Max Clock Mem Offset Mem CLK Peak Voltage Initial Test Endurance
1037.8 1252.8 1.012 Pass  
50 1087.6 1252.8 1.012 Pass  
100 1137.5 1252.8 1.012 Pass  
135 1172.3 1252.8 1.012 Pass Pass
135 1172.3 100 1300.5 1.012 Pass  
135 1172.3 200 1352.9 1.012 Pass  
135 1172.3 300 1404 1.012 Pass  
135 1172.3 400 1453.5 1.012 Pass Pass
135 1172.3 600 - 1.012 Fail
Driver Crash

Once we merged the overclocks and conducted endurance testing, we ended with a CPU OC to 4.0GHz and GPU OC to 1172.3MHz, with a 1453.5MHz memory clock. That's a healthy OC – particularly for a laptop, which have historically been incapable of overclocks.

The concern, of course, is with thermals. You're definitely not removing the AC and retaining overclocks, so portability is instantly removed, and the smaller enclosure with limited, effectively immutable cooling solutions will be more prone to overheating with overclocks. Laptop components are also harder to replace – if not impossible, in some instances – and make the risk incurred from damage significantly higher. These combine to make overclocking generally unapproachable on laptops, but there are still instances where it's worth, in the very least, a short-term overclock. We'll uncover those below.

And, just for comparison, here's the GT72 Dominator Pro G with GTX 980 (previous review):

GPU OC - GT72 Dominator Pro G w/ GTX 980
CLK Offset Max Clock Mem Offset Mem CLK Peak Voltage Initial Test Endurance
1227 3499 1.125 Pass Pass
100 1327 3499 1.125 Pass -
120 1335 3499 1.125 Pass  
150 1365 3499 1.125 Pass  
180 1395 3499 1.125 Pass  
210 1437 3499 1.125 Pass  
230 1445 3499 1.125 Pass  
230 1445 20 3518 1.125 Pass  
230 1445 40 3542 1.125 Pass  
230 1445 60 3557 1.125 Pass  
230 1445 80 3580 1.125 Pass  
230 1445 100 3600 1.125 Pass  
230 1445 140 3637 1.125 Pass  
230 1445 160 3662 1.125 Pass  
240 1467 160 3662 1.125 Pass  
250 1475 180 3682 1.125 Fail  
250 1475 160 3662 1.125 Fail  
230 1445 160 3662 1.125 Pass Fail
220 1440 80 3580 1.125 Pass Fail
200 1405 80 3580 1.125 Pass Pass

Fangbook 4 Temperatures – Overclocked vs. Stock

This thermal benchmark strictly compares the overclocked configuration against the stock configuration. Some previous laptops can also be found in the equilibrium metrics.



The above chart shows thermals at equilibrium – when their stable, unchanging temperature is achieved under a heavy workload. The Fangbook 4's GTX 970M silicon rests at 41.30C (delta T over ambient) when at its stock clocks. Temperature increases marginally (9.44 percent difference) when overclocking the GPU and CPU in conjunction. The i7-6820HK has a very slight increase in thermals (39.01C to 42.82C) post-overclock. 2.7GHz Turbo Boosts to 3.6GHz when the system is under load, which is the case for the above chart.



Above are two thermals-over-time charts, one of our most unique methods for data presentation. The thermal benchmark is automated, and so the test cases exhibit perfectly synchronized ramp-up time as idle logging transitions to workload benchmarking.

The wave action you're observing (most obvious in the GPU chart) is the fan's self-regulation. We allowed the laptop to control its own fan speeds, whereupon PWM is used to make trade-offs between noise and thermals. Once a certain threshold is met (appears to be ~45C delta T), the fan RPM bumps-up and drops the thermals, then spins back down.

Continue to the next page for application workload benchmarks and real-world gaming benchmarks.

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Last modified on January 26, 2016 at 1:00 pm
Steve Burke

Steve started GamersNexus back when it was just a cool name, and now it's grown into an expansive website with an overwhelming amount of features. He recalls his first difficult decision with GN's direction: "I didn't know whether or not I wanted 'Gamers' to have a possessive apostrophe -- I mean, grammatically it should, but I didn't like it in the name. It was ugly. I also had people who were typing apostrophes into the address bar - sigh. It made sense to just leave it as 'Gamers.'"

First world problems, Steve. First world problems.

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