Power Consumption

For our regular readers, the topic of power consumption has been an interesting one as of late. For the most part, Intel’s consumer processors have been under their expected power consumption, but the recent Skylake-X processors seem to have put that notion out to sea, with numbers almost 20% above what is expected at full load.

The Thermal Design Power (TDP) of a processor is the capability required to adequately cool that processor - while it is not the exact power consumption, is a rough indication of how much power a processor is likely to consume. Higher cooling requirements give to a higher TDP, which naturally fit into a chip that consumes more power. Our last review of consumer processors, the Kaby Lake 7th Generation chips, showed that the Core i7-7700K consumed pretty much exactly the TDP of the chip, while the Core i5 processors came in under their TDP rating by a large margin. The Coffee Lake processors follow this trend

Power: Total Package (Full Load)

The Core i7-8700K has a TDP of 95W, but consumes 86.2W at full load, of which the cores account for 78.6W. The rest of the power is consumed mostly by the uncore and the memory controller.

The Core i5-8400 is rated at 65W, and consumes only 49.3W at full load, of which 41.7W is from the cores. That leaves 7.6W on the table for the uncore and memory controller, which is almost identical to that of the Core i7-8700K, showing the similarity in design.

Test Bed and Setup

As per our processor testing policy, we take a premium category motherboard suitable for the socket, and equip the system with a suitable amount of memory running at the manufacturer's maximum supported frequency. This is also typically run at JEDEC subtimings where possible. It is noted that some users are not keen on this policy, stating that sometimes the maximum supported frequency is quite low, or faster memory is available at a similar price, or that the JEDEC speeds can be prohibitive for performance. While these comments make sense, ultimately very few users apply memory profiles (either XMP or other) as they require interaction with the BIOS, and most users will fall back on JEDEC supported speeds - this includes home users as well as industry who might want to shave off a cent or two from the cost or stay within the margins set by the manufacturer. Where possible, we will extend out testing to include faster memory modules either at the same time as the review or a later date.

Test Setup
Processor Intel Core i7-8700K (6C/12T, 95W, 3.8 GHz)
Intel Core i5-8400 (6C/6T, 65W, 2.8 GHz)
Motherboards GIGABYTE Z370 Gaming 7
Cooling Silverstone Argon AR10-115XS
Power Supply Corsair AX760i PSU
Memory Corsair Vengeance Pro DDR4-2666 4x8 GB
Video Cards MSI GTX 1080 Gaming 8GB
Hard Drive Crucial MX200 1TB
Optical Drive LG GH22NS50
Case Open Test Bed
Operating System Windows 10 Pro 64-bit

Many thanks to...

We must thank the following companies for kindly providing hardware for our multiple test beds. Some of this hardware is not in this test bed specifically, but is used in other testing.

Thank you to Sapphire for providing us with several of their AMD GPUs. We met with Sapphire back at Computex 2016 and discussed a platform for our future testing on AMD GPUs with their hardware for several upcoming projects. As a result, they were able to sample us the latest silicon that AMD has to offer. At the top of the list was a pair of Sapphire Nitro R9 Fury 4GB GPUs, based on the first generation of HBM technology and AMD’s Fiji platform. As the first consumer GPU to use HDM, the R9 Fury is a key moment in graphics history, and this Nitro cards come with 3584 SPs running at 1050 MHz on the GPU with 4GB of 4096-bit HBM memory at 1000 MHz.

Further Reading: AnandTech’s Sapphire Nitro R9 Fury Review

Following the Fury, Sapphire also supplied a pair of their latest Nitro RX 480 8GB cards to represent AMD’s current performance silicon on 14nm (as of March 2017). The move to 14nm yielded significant power consumption improvements for AMD, which combined with the latest version of GCN helped bring the target of a VR-ready graphics card as close to $200 as possible. The Sapphire Nitro RX 480 8GB OC graphics card is designed to be a premium member of the RX 480 family, having a full set of 8GB of GDDR5 memory at 6 Gbps with 2304 SPs at 1208/1342 MHz engine clocks.

Further Reading: AnandTech’s AMD RX 480 Review

With the R9 Fury and RX 480 assigned to our gaming tests, Sapphire also passed on a pair of RX 460s to be used as our CPU testing cards. The amount of GPU power available can have a direct effect on CPU performance, especially if the CPU has to spend all its time dealing with the GPU display. The RX 460 is a nice card to have here, as it is powerful yet low on power consumption and does not require any additional power connectors. The Sapphire Nitro RX 460 2GB still follows on from the Nitro philosophy, and in this case is designed to provide power at a low price point. Its 896 SPs run at 1090/1216 MHz frequencies, and it is paired with 2GB of GDDR5 at an effective 7000 MHz.

We must also say thank you to MSI for providing us with their GTX 1080 Gaming X 8GB GPUs. Despite the size of AnandTech, securing high-end graphics cards for CPU gaming tests is rather difficult. MSI stepped up to the plate in good fashion and high spirits with a pair of their high-end graphics. The MSI GTX 1080 Gaming X 8GB graphics card is their premium air cooled product, sitting below the water cooled Seahawk but above the Aero and Armor versions. The card is large with twin Torx fans, a custom PCB design, Zero-Frozr technology, enhanced PWM and a big backplate to assist with cooling.  The card uses a GP104-400 silicon die from a 16nm TSMC process, contains 2560 CUDA cores, and can run up to 1847 MHz in OC mode (or 1607-1733 MHz in Silent mode). The memory interface is 8GB of GDDR5X, running at 10010 MHz. For a good amount of time, the GTX 1080 was the card at the king of the hill.

Further Reading: AnandTech’s NVIDIA GTX 1080 Founders Edition Review

Thank you to ASUS for providing us with their GTX 1060 6GB Strix GPU. To complete the high/low cases for both AMD and NVIDIA GPUs, we looked towards the GTX 1060 6GB cards to balance price and performance while giving a hefty crack at >1080p gaming in a single graphics card. ASUS lended a hand here, supplying a Strix variant of the GTX 1060. This card is even longer than our GTX 1080, with three fans and LEDs crammed under the hood. STRIX is now ASUS’ lower cost gaming brand behind ROG, and the Strix 1060 sits at nearly half a 1080, with 1280 CUDA cores but running at 1506 MHz base frequency up to 1746 MHz in OC mode. The 6 GB of GDDR5 runs at a healthy 8008 MHz across a 192-bit memory interface.

Further Reading: AnandTech’s ASUS GTX 1060 6GB STRIX Review

Thank you to Crucial for providing us with MX200 SSDs. Crucial stepped up to the plate as our benchmark list grows larger with newer benchmarks and titles, and the 1TB MX200 units are strong performers. Based on Marvell's 88SS9189 controller and using Micron's 16nm 128Gbit MLC flash, these are 7mm high, 2.5-inch drives rated for 100K random read IOPs and 555/500 MB/s sequential read and write speeds. The 1TB models we are using here support TCG Opal 2.0 and IEEE-1667 (eDrive) encryption and have a 320TB rated endurance with a three-year warranty.

Further Reading: AnandTech's Crucial MX200 (250 GB, 500 GB & 1TB) Review

Thank you to Corsair for providing us with an AX860i PSU. The AX860i commands a 860W rating at 50C with 80 PLUS certification. This allows for a minimum 89-92% efficiency at 115V and 90-94% at 230V. The AX860i is completely modular, running the larger 200mm design, with a dual ball bearing 140mm fan to assist high-performance use. The AX860i is designed to be a workhorse, with plenty of PCIe connectors for suitable GPU setups. The AX860i also comes with a Zero RPM mode for the fan, which due to the design allows the fan to be switched off when the power supply is under 30% load.

Further Reading: AnandTech's Corsair AX1500i Power Supply Review

Thank you to G.Skill for providing us with memory. G.Skill has been a long-time supporter of AnandTech over the years, for testing beyond our CPU and motherboard memory reviews. We've reported on their high capacity and high-frequency kits, and every year at Computex G.Skill holds a world overclocking tournament with liquid nitrogen right on the show floor.

Further Reading: AnandTech's Memory Scaling on Haswell Review, with G.Skill DDR3-3000

Intel vs AMD: The Start of Core Wars Benchmark Overview


View All Comments

  • yeeeeman - Thursday, October 5, 2017 - link

    Well, you either have bad inspiration or you chose the CPUs from AMD that most people won't buy.
    You are missing R7 1700 and R5 1600 which are ~ same as new Intel offerings in computing tasks but they cost less. So...
  • watzupken - Thursday, October 5, 2017 - link

    I don't know how you define as "best" for review graph. The point is that we are seeing new 6 cores solution from Intel, so very logically, people will be trying to compare apples with apples, i.e. 6 core solutions from both camps. So omitting the results from 1600 actually looks more than meets the eye to me, especially when you folks previously did a R5 1600X review. Reply
  • Ian Cutress - Thursday, October 5, 2017 - link

    I'm adding the R5 1600 data. It'll take 10-15 minutes, it's not a quick process. brb Reply
  • watzupken - Thursday, October 5, 2017 - link

    Thank you Ian. Please do add the data for R5 1600/X. From what I read elsewhere, it appears there is good competition between the Core i5 and R5 1600/X series. Reply
  • Ian Cutress - Thursday, October 5, 2017 - link

    OK, should be added. You might have to CTRL+F5 to clear the cache to see the updated versions. Reply
  • WinterCharm - Thursday, October 5, 2017 - link

    Thanks Ian!

    It really is the most logical and fair comparison.
  • WinterCharm - Thursday, October 5, 2017 - link

    You really should have chosen SIMILARLY priced chips (So, 1700 / 1600 / 1600X) because it would have shown "here's the performance you get per dollar" which ultimately is what matters. Reply
  • Ian Cutress - Thursday, October 5, 2017 - link

    My ultimate goal is to have a graph widget that lets you select which CPU you want to focus on, and it automatically pulls in several around that price point as well as some of the same family. I'm not that skilled, though Reply
  • Error415 - Thursday, October 5, 2017 - link

    Performane per dollar doesn't matter, out right performance matters. SMH, only a fool buys the second best cpu when the best is only a few dollars more. Reply
  • zuber - Thursday, October 5, 2017 - link

    You basically just said "performance per dollar doesn't matter, only a fool ignores performance per dollar". Reply

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