Power Consumption At The FX-8370E's Stock Clock Rate
Test System And Measurement Methodology
Our German lab went the extra mile for drilling down into power consumption, cutting the braiding from our power supply's cables to give us the same measurement capabilities you've seen in our graphics card launch coverage. The readings are based on the four-channel HAMEG HMO 3054 oscilloscope.
We’ll first take a look at the power consumption, which we measured via the motherboard’s power connector and includes any losses due to the voltage regulators. Depending on load, these losses can reach eight percent. Because the ASRock motherboard AMD sent over doesn’t let us analyze the VR data, we weren’t able to factor out those losses, though. The FX-8370E’s actual power consumption is a bit lower than the values reported here.
| Test System | |
|---|---|
| System | AMD FX-8370Ebe quiet! Dark Rock Pro Air Coolerbe quiet! Shadow Rock Slim Air CoolerASRock Fatal1ty 990FX Killer16 GB Radeon DDR3-1866Samsung 850 EVO 512 GBbe quiet! Dark Power Pro 1200 WMicrocool Banchetto 101 |
| Methodology | No-contact current measurement at all railsVoltage measurementIR real-time monitoring |
| Equipment | 1 x HAMEG HMO3054, 500 MHz Four-Channel Oscilloscope4 x HAMEG HZO50 Current Probe4 x HAMEG HZ355 (10:1 Probe, 500 MHz)1 x HAMEG HMC8012 DSO1 x Optris PI450 80 Hz Infrared Camera + PI Connect |
Optris' PI450 is an infrared camera that was developed specifically for process monitoring. It supplies real-time thermal images at a rate of 80 Hz. The pictures are sent via USB to a separate system, where they can be recorded as video. The PI450’s thermal sensitivity is 40 mK, making it ideal for assessing small gradients.
We're also using be quiet! Dark Rock Pro. It’s a large dual-tower cooler with two fans that spin based on the CPU’s temperature. Even our highest overclock doesn’t pose a problem for it. As a result, the fans max out at 800 RPM, and our acoustic measurement equipment can’t pick it up. So, we're forgoing our usual noise level measurements.
Even after a lengthy test run, idle temperatures are extremely low. We start a new benchmark once the heat pipe cools down to 30 degrees Celsius.
Because we want to uncover the sweet spots for overclocking, voltage, and cooling, we’ll switch out the Dark Rock Pro CPU cooler for a less expensive model later, and then make our recommendation.
Here's another of the motherboard's shortcomings: a measurement of 75 degrees is way too high for a chipset at idle. We even measured well over 80 degrees Celsius on the chipset’s surface after running the motherboard inside of a case. That's enough to hurt your fingers, as I now know from experience.
AMD FX-8370E at 3.3 GHz
Core Voltage
The core voltage, provided by the VRM, plays a prominent role in determining power consumption and how much waste heat is produced. A real 1.17 V reading is a bit lower than the BIOS setting of 1.1850 V. Interestingly, the value fluctuates a lot when the BIOS is set to regulate voltage automatically, whereas it doesn't if you switch the firmware to manual control.
The Turbo Core clock rate falls all the way to the base frequency during our stress test.
Power Consumption
At idle, we’re looking at 17 W. Under a taxing load, that number jumps to 75 W measured at the rail supplying the CPU. This is both unexpected and pleasant. It's the sort of power figure we've always wanted to see from a top-end AMD processor. After all, once the voltage regulator losses are calculated, we should be looking at right around 65 to 68 W. Sure, Intel's CPUs are lower still (and a great many faster, too), but not as far as you’d think.
Temperatures
A lower-power processor is bound to demonstrate better thermal performance. And indeed, the temperatures we're reporting are good at idle and under load. We could have probably used AMD's stock cooler without creating a bunch of annoying noise.
Heat pipes on the cooler we did use only warm up to 34 degrees Celsius. A 40-degree core temperature is also impressive.
Looking at the power consumption-to-performance ratio, we have a really interesting eight-core CPU that’s definitively better than what AMD offered previously in the FX family. Even though a lower clock rate results in a performance hit, the FX-8370E is exactly what we were hoping to see from AMD to begin with.