Power Consumption Measurement Methodology
Tom’s Hardware Germany’s test system for the exact measurement of graphics cards’, CPUs’, and other components’ power consumption was developed in cooperation with HAMEG (Rohde & Schwarz). It was designed for particularly precise measurements with very small time intervals and has a temporal resolution of up to 1 ms.
Only sophisticated technology is able to handle the challenges presented by AMD’s PowerTune and Nvidia’s Boost technologies. These generate changes in core voltage in time frames of under 10 ms, which results in very large and quick voltage fluctuations. Let’s take a look at what can happen in the space of only one single millisecond, using measurement intervals of 10 μs.
This is why we’re evaluating all measured currents and voltages with a 500 MHz four-channel oscilloscope with a data logger, the HAMEG HMO3054, and extremely fast current probes. This setup also allows for unified data storage and remote control.
The measurements provided by the three high-resolution DC current probes, all HAMEG HZO50s, are taken via a riser card for the 3.3 V and 12 V rails, which we constructed specifically for this purpose. It supports PCIe 3.0 and uses short signal paths. The remaining probes are connected to the PCIe power cable that we modified for this.
We measure the voltages directly at their respective rails. We’re now working with a temporal resolution of 1 ms, since this allows us to record and evaluate the fluctuations caused by AMD’s PowerTune and Nvidia’s Boost technologies with confidence.
We’ve limited the measurement duration to 1 minute due to the very high volume of data when we measure all channels. We only shorten the measurement intervals all the way to the minimum that the physical capabilities of our setup allows for our more detailed measurements.
| Test Methodology | No Contact Current Measurement at All Rails Direct Voltage Measurement IR Real-Time Monitoring |
|---|---|
| Test Equipment | 1 x HAMEG HMO3054, 500 MHz Four-Channel Oscilloscope with Data Logger 4 x HAMEG HZO50 Current Probe 4 x HAMEG HZ355 (10:1 Probe, 500 MHz) 1 x HAMEG HMC8012 DSO with Data Logger 1 x Optris PI450 80 Hz Infrared Camera + PI Connect |
| Test System | Intel Core i7-5960X MSI X99 Gaming 7 16GB G.Skill Ripjaws DDR4 2666 (4 x 4GB) Samsung 850 EVO 512 GB Raijintek Water Cooling be quiet! Dark Power Pro 1200W Microcool Banchetto 101 |
Benchmarking Hardware And Software
The Radeon R9 285 was tested with the 14.8 beta launch driver, but all other AMD cards were outfitted with the Catalyst 14.7 RC1 for testing. The GeForce cards used the newest option, which at the time of testing was the 340.52 WHQL driver.
We selected a variety of newer game titles with high detail settings at a resolution of 1920x1080 in order to give the Radeon R9 285 and its competitors a solid, real-world workload that this class of card should be able to handle.
The Asus Radeon R9 285's core clock was dropped to the 918 MHz reference specification in order to show what a typical Radeon R9 285 should be able to accomplish. Keep in mind that there is no reference cooler for this card, so all Radeon R9 285 will be unique in this respect.
Some readers will note that the Radeon R9 280 results are those we collected from our Sapphire Dual-X Radeon R9 280 review. Sapphire's card comes with a 940 MHz core clock, a mere 7 MHz over the reference specification. We took a few benchmarks with the reference clock but quickly realized that the results are within the margin of error, so we're using the Sapphire numbers to represent reference Radeon R9 280 results. Keep in mind that there is no reference Radeon R9 280 cooler, either.
Two of the games we're testing have an option to use a Mantle code path, so we're running those benchmarks (Thief and Battlefield 4) with Mantle enabled and disabled to measure the API's impact.
Graphics cards like the Radeon R9 280 require a substantial amount of power, so XFX sent us its PRO850W 80 PLUS Bronze-certified power supply. This modular PSU employs a single +12 V rail rated for 70 A. XFX claims continuous (not peak) output of up to 850 W at 50 degrees Celsius.

We've almost exclusively eliminated mechanical disks in the lab, preferring solid-state storage for alleviating I/O-related bottlenecks. Samsung sent all of our labs 256 GB 840 Pros, so we standardize on these exceptional SSDs.
| Test System | |||||
|---|---|---|---|---|---|
| CPU | Intel Core i7-3960X (Sandy Bridge-E), 3.3 GHz, Six Cores, LGA 2011, 15 MB Shared L3 Cache, Hyper-Threading enabled. | ||||
| Motherboard | ASRock X79 Extreme9 (LGA 2011) Chipset: Intel X79 Express | ||||
| Networking | On-Board Gigabit LAN controller | ||||
| Memory | Corsair Vengeance LP PC3-16000, 4 x 4 GB, 1600 MT/s, CL 8-8-8-24-2T | ||||
| Graphics | Asus Strix Radeon R9 285 954 MHz GPU, 2 GB GDDR5 at 1375 MHz (5500 MT/s) (underclocked GPU to reference 918 MHz specification for benchmarks) AMD Radeon R9 280X 850/100 MHz GPU, 3 GB GDDR5 at 1500 MHz (6000 MT/s) Sapphire Dual-X R9 280 OC 850/940 MHz GPU, 3 GB GDDR5 at 1250 MHz (5000 MT/s) AMD Radeon R9 270X 1050 MHz GPU, 2 GB GDDR5 at 1400 MHz (5600 MT/s) Nvidia GeForce GTX 660 980/1033 MHz GPU, 2 GB GDDR5 at 1502 MHz (5008 MT/s) Nvidia GeForce GTX 760 980/1033 MHz GPU, 2 GB GDDR5 at 1502 MHz (5008 MT/s) Nvidia GeForce GTX 770 1046/1085 MHz GPU, 2 GB GDDR5 at 1752 MHz (7008 MT/s) | ||||
| SSD | Samsung 840 Pro, 256 GB SSD, SATA 6Gb/s | ||||
| Power | XFX PRO850W, ATX12V, EPS12V | ||||
| Software and Drivers | |||||
| Operating System | Microsoft Windows 8 Pro x64 | ||||
| DirectX | DirectX 11 | ||||
| Graphics Drivers | Radeon R9 285: AMD Catalyst 14.8 beta All other Radeon cards: AMD Catalyst14.7 RC 1 All GeForce Cards: Nvidia 340.52 WHQL | ||||
| Benchmarks | |||||
|---|---|---|---|---|---|
| Watch Dogs | Version 1.04.497, Custom THG Benchmark, 90-sec FRAPS, Driving | ||||
| Arma 3 | V. 1.26.126.789, 30-sec. Fraps "Infantry Showcase" | ||||
| Battlefield 4 | Version 1.3.2.3825, Custom THG Benchmark, 90-Sec | ||||
| Assassin's Creed IV: Black Flag | Custom THG Benchmark, 40-Sec | ||||
| Thief | Version 1.6.0.0, Built-in Benchmark | ||||
| Titanfall | Version 1.0.5.7, Demeter Map, Custom THG Benchmark | ||||
| Grid Autosport | Version 1.0.101.4672, Built-In benchmark | ||||
| Far Cry 3 | Version 1.05, Custom THG Benchmark, 55-sec FRAPS | ||||
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- The Radeon's GCN Is Updated Again: The Tonga GPU
- Asus Strix Radeon R9 285
- Gigabyte R9 285 WindForce OC
- Test Setup and Benchmark Suite
- Synthetic Benchmark Results
- Titanfall and Battlefield 4 Results
- Thief and Arma 3 Results
- Grid Autosport and Assassin's Creed IV Results
- Watch Dogs and Far Cry 3 Results
- Idle Power Consumption Results
- Gaming Power Consumption Results
- GPGPU Power Consumption Results
- Temperature and Noise Results
- Radeon R9 285 Holds its Own at $250





Good to see AMD have tackled the noise and temperature issues that have plagued it's previous 28nm cards as well but it's a bit late in the day given that 20nm shouldn't be to far off now.
Also, on the last page, you guys wrote R7 270X instead of R9, and in the chart it says "Relative to Radeon HD 7950 Boost". Oh, and in the Pros section, it says the 285 has R9 260 like performance?
[EDIT by Cleeve]
Thanks for the proofread, fixing it now!
[/edit]
I prefer get a r9 280 and downclock get same results. I can't see the point of this heat on graphics. maybe drivers. OR THIS IS HAWAII XT! Too much Heat!
I think the guys see if they hit the OC the room Will burn! maybe a problem with drivers.
Last time i see that Heat 290x tests. lol!
But in fact, the memory interface was cut by a third (384 bit -> 256 bit), not half.
[Edit by Cleeve]
Good point, fixed! Thx.
[/edit]
[Edit by Cleeve]
Good catch, fixed but might take a while to populate.
[/Edit]
Faster memory would have helped but more would not have made much of a difference: most of the extra memory on GPUs with more memory channels gets filled with extra copies of resources to improve availability. Without those extra channels, filling more RAM with extra copies would make little difference.
The R7 265 is faster than the R7 260X, yet the R9 285 is slower than the R9 280X?
The R7 265 is faster than the R7 260X, yet the R9 285 is slower than the R9 280X?
Yea this should have been named 275 or 275x.
The 280X probably should have been the 285, and this card should have been released as the 280X. Or it could be next-gen; call it the 380 or 375.
The 270/280 are just rehashes of HD7xxx designs while the 285 is a cut-down 290... and the 285 does beat the 280 enough times to earn its place in the 28x range.
Give the 285 a 6GT/s memory interface and it would slot in more solidly between the 280 and 280X.
The R7 265 is faster than the R7 260X, yet the R9 285 is slower than the R9 280X?
Indeed, naming schemes are always kind of bogus.
260< 260X < 265
280<=285< 280X
That's just the way it is.