Hardware-Based Security Fixes, Architecture & Test Setup
Much like the Cascade and Whiskey Lake processors we recently covered, Intel's Coffee Lake refresh comes with hardware-based mitigations for the Meltdown and L1TF (Foreshadow) vulnerabilities. Current Spectre and Meltdown mitigations, which Intel delivers via software and microcode patches, can reduce performance by up to 10% on newer CPUs, with older hardware suffering even larger losses. The new mitigations, baked directly into the silicon, should reduce or even eliminate the performance impact for a few vulnerabilities.
|Vulnerability||Coffee Lake Refresh/Whiskey Lake Mitigation||Cascade Lake Mitigation|
|Variant 1 (Spectre)||Operating System||Operating System/VMM|
|Variant 2 (Spectre)||Microcode + Operating System||In-Silicon + Operating System/VMM|
|Variant 3 (Meltdown)||In-Silicon||In-Silicon|
|Variant 3a||Microcode + Operating System||Firmware|
|Variant 4||Microcode + Operating System||Microcode + Operating System/VMM|
As we're learning, it may take several processor generations before the fixes for all vulnerabilities are applied at a silicon level. Intel's ninth-gen CPUs do still need a combination of microcode and operating system patches. But at least Meltdown and L1TF Foreshadow are patched fully in hardware.
Although we don't have much new information about Coffee Lake refresh architectural changes, David Schoor at WikiChip says the new chips use a familiar ring bus, an internal high-speed pathway connecting the cores and cache.
This stands in contrast to the mesh architecture (deep dive here) that Intel uses on its high-end desktop models, including the eight-core Core i7-7820X. We've found that the mesh architecture has a negative impact on some desktop applications, including games, which Intel acknowledges. The mesh architecture was designed to increase scalability as it expands to higher core counts in the Xeon family.
Overclocking, Rounds One and Two
We tapped Corsair's H115i v2 to test our Core i9-9900K sample in the U.S. lab. This liquid cooler afforded enough headroom to sustain a 5.0 GHz overclock with a 1.33V Vcore and a Load Line Calibration 4 setting. It kept the chip at a steady 85°C during extended non-AVX stress tests. Folding in AVX instructions did, unfortunately, overwhelm the all-in-one. To reign in the thermal output, we set the AVX offset to -2, meaning the chip ran at 4.8 GHz during AVX-optimized workloads and 5.0 GHz in the absence of AVX instructions. We maintained a temperature of 95°C during three hours of Prime95 using those settings.
To model real-world settings attainable by enthusiasts with closed-loop liquid coolers, we applied the -2 AVX offset for our 5.0 GHz overclock in the gaming, office and productivity, and rendering tests.
We did not use an offset for the workstation graphics, compute, power consumption, and temperatures sections.
MEG Z390 Godlike
We're using MSI's MEG Z390 Godlike as our test platform for all Intel processors. This pricey board retails for $600, but has the power delivery subsystem to support aggressive overclocking.
The MSI MEG Z390 Godlike sits at the top of MSI's motherboard hierarchy. It has a decked-out 18-phase power delivery subsystem that's designed to squeeze every drop of performance out of Intel's new processors. It also comes with a few nifty accessories like an M.2 PCIe riser card and an HDMI streaming card.
|Test System & Configuration|
|Hardware||Germany Intel LGA 1151 (Z390)Intel Core i9-9900K, i7-9700K, i5-9600K, i7-8700K, i5-8600K, i5-8400MSI MEG Z390 Godlike2x 8GB G.Skill FlareX DDR4-3200 @ DDR4-2667 & DDR4-3466AMD Socket AM4 (400-Series)AMD Ryzen 7 and Ryzen 5 MSI X470 Gaming M7 AC 2x 8GB G.Skill FlareX DDR4-3200 @ DDR4-2667, DDR4-3466Intel LGA 2066 Intel Core i7 MSI X299 Gaming Pro Carbon AC 4x 8GB G.Skill FlareX DDR4-3200 @ DDR4-2666All SystemsGeForce GTX 1080 Founders Edition (Gaming) Nvidia Quadro P6000 (Workstation)1x 1TB Toshiba OCZ RD400 (M.2, System SSD) 4x 1TB Crucial MX300 (Storage, Images)be quiet! Dark Power Pro 11, 850W Windows 10 Pro (All Updates)U.S. Intel LGA 1151 (Z390)Intel Core i9-9900K, i7-9700K, i5-9600K, i7-8700K, i5-8600K, i5-8400MSI MEG Z390 Godlike2x 8GB G.Skill FlareX DDR4-3200 @ DDR4-2667 & DDR4-3466Intel LGA 2066Intel Core i9-7820XMSI X299 Gaming Pro Carbon AC4x 8GB G.Skill FlareX DDR4-3200 @ DDR4-2666, DDR4-3200AMD Socket AM4 (400-Series)AMD Ryzen 7 2700X, Ryzen 5 2600XMSI X470 Gaming M7 AC2x 8GB G.Skill FlareX DDR4-3200 @ DDR4-2933All SystemsEVGA GeForce GTX 1080 FE 1TB Samsung PM863SilverStone ST1500-TI, 1500WWindows 10 Pro (All Updates)|
|Cooling||GermanyAMD Wraith RipperAlphacool Ice Block XPXEnermax LiqTech 240 TR4Thermal Grizzly KryonautU.S.Wraith RipperCorsair H115iEnermax Liqtech 240 TR4 II|
|Power Consumption Measurement||Contact-free DC Measurement at PCIe Slot (Using a Riser Card) Contact-free DC Measurement at External Auxiliary Power Supply Cable Direct Voltage Measurement at Power Supply 2x Rohde & Schwarz HMO 3054, 500 MHz Digital Multi-Channel Oscilloscope with Storage Function4x Rohde & Schwarz HZO50 Current Probe (1mA - 30A, 100 kHz, DC) 4x Rohde & Schwarz HZ355 (10:1 Probes, 500 MHz) 1x Rohde & Schwarz HMC 8012 Digital Multimeter with Storage Function|
|Thermal Measurement||1x Optris PI640 80 Hz Infrared Camera + PI Connect Real-Time Infrared Monitoring and Recording|
|Acoustic Measurement||NTI Audio M2211 (with Calibration File, Low Cut at 50Hz) Steinberg UR12 (with Phantom Power for Microphones)Creative X7, Smaart v.7 Custom-Made Proprietary Measurement Chamber, 3.5 x 1.8 x 2.2m (L x D x H) Perpendicular to Center of Noise Source(s), Measurement Distance of 50cm Noise Level in dB(A) (Slow), Real-time Frequency Analyzer (RTA) Graphical Frequency Spectrum of Noise|
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