Power, Overclocking and Test Setup
Power consumption measurements are always a bit tricky. But as long as your 12V supply (EPS) readings, motherboard power supply sensor values, and voltage transformer losses plausibly coincide, everything is fine. Therefore, we're using pure package power to avoid possible influences from our motherboard. Results from the PWM controller are very reliable if you take them as averages over a few minutes.
We conducted this round of limited testing in our U.S. lab, and our results are not directly comparable with numbers from the German lab used in previous reviews.
We expected high power consumption from the Core i9-9980XE, and Intel's flagship didn't disappoint. At stock settings, we recorded 245W from AVX-optimized workload and 199W in a stress test that didn't use AVX instructions. Fortunately, our Corsair H115i closed-loop liquid cooler proved ample with its fans in performance mode. The H115i maintained temperatures below 75°C during an extended session of Prime95 and 65°C during a non-AVX stress test.
Those numbers skyrocketed when we began overclocking. At 4.4 GHz, we observed 256W during an SSE-optimized stress test and 348W with AVX instructions in play (in spite of a relatively tame 3.3 GHz AVX offset). The new Blender benchmark is an effective power benchmark, too: the Core i9-9980XE consumed up to 392W during its render.
As with the Skylake-X processors we already reviewed, current has a big impact on both performance and heat. It's even possible to generate higher performance scores in threaded benchmarks like Cinebench by using a higher VCCIN voltage setting (at a given frequency).
Unfortunately, Intel didn't give us much time with the Core i9-9980XE before lifting its embargo, so we don't have a complete suite of overclocked benchmark results yet. But we did experiment, dialing the VCCIN to 1.92V and upping Vcore to 1.1V for a 4.4 GHz overclock. We also dialed back the AVX offset to -11, yielding 3.3 GHz, along with a -16 AVX-512 offset to run the processor at its stock 2.8 GHz during the most taxing AVX-optimized workloads. Even with our offsets in place, we saw up to 95°C during the Blender benchmark and 90°C in an extended non-AVX stress test.
Even with our relaxed settings, heat easily overwhelmed our H115i after small voltage increases, and that was with its fans cranking away at maximum speed. Just like the first-gen Skylake-X chips, thermals limited our overclocking efforts before hitting the silicon's limits, despite solder-based TIM. Build your own custom loop if you plan on serious overclocking. Also, we advise forced air or water cooling on the power delivery subsystem. Invest in a PSU able to deliver at least 20A on the +12V rail. MSI’s BIOS warns that you need a power supply capable of providing up to 1000W through the eight-pin EPS cable; a beefy PSU is non-negotiable.
|Test System & Configuration|
Intel LGA 2066
AMD Socket SP3 (TR4)
AMD Ryzen 7 2700X
MSI X470 Gaming M7 AC
2x 8GB G.Skill FlareX DDR4-3200 @ DDR4-2933
Intel LGA 1151 (Z390)
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