Test System and Measurement Method
We partnered up with HAMEG Instruments (Rohde & Schwarz) to implement a state-of-the-art test system for precise, short interval power and performance measurements.
Only modern lab instruments can keep up with the challenges that AMD’s Power Tune and Nvidia’s GPU Boost present (namely, huge swings in dynamic power consumption). We feed all relevant currents and voltages into a multi-channel 500 MHz oscilloscope (HAMEG HMO 3054), which can be remote-controlled and is able to retain the test data.
We measure the currents with three calibrated DC current clamp probes (HAMEG HZO50). Two of them, 3.3 and 12 V, take their readings at a custom-made riser card, which can reliably pass PCIe 3.0 signals, and one of them at a specially-modified PCIe power cable. All voltages are measured at the single-rail power supply, which we slightly modified to allow better access.
Our time resolution is now a mere 2 ms, which can measure and log all load transients incurred by AMD’s Power Tune and Nvidia’s GPU Boost. In order to keep the volume of data manageable, we limit the duration of a test run to two minutes.
| Test Method | No contact current measurement at the PCIe slot (Riser card) No contact current measurement at the external PCIe power cable Voltage measurement at the PSU |
|---|---|
| Test Equipment | 1 x HAMEG HMO 3054, 500 MHz four-channel oscilloscope 3 x HAMEG HZO50 current probe (1 mA - 30 A, 100 kHz, DC) 4 x HAMEG HZ355 (10:1 probe, 500 MHz) 1 x HAMEG HMC 8012 DSO |
| Test Bench | Microcool Banchetto 101 |
| Power Supply | Corsair AX860i with slightly modified connectors |
What Happens Within 100 ms?
A lot! We log the power draw with three probes at a 2 ms interval and pick a representative 100 ms window. Then we plot the resulting 50 data points in a graph.
Looking at the graph, you almost have to feel sorry for the power supply. Power draw through the PCIe power cables jumps from 140 to 352 W within a few milliseconds. You can't expect just any old generic PSU to cope with that. The two test points at the PCIe riser cards do not exhibit such drastic load changes.

We like that neither AMD nor Nvidia max out the PCIe slot connector's output rating, which is 75 W. Those auxiliary power cables bear the brunt of the load. Nor are there drastic load transients on the motherboard connector. All of this helps ensure system stability, benefiting multi-GPU setups in particular.
Now let's take a look at power consumption in real-world workloads.

Well, since you are comparing a non reference GPU, you should take also a non-reference GPU to compare.
Tom's using Gigabyte's 780ti OC which costs the same as the reference card...
So even the non-reference models are on a different tier as well as their reference...
Typical translation errors, the original is in metric
http://www.tomshardware.de/powercolor-r9-290x-pcs-review,testberichte-241519-3.html4
I will clearify with Chris, that we use both in the future. Metric is worldwide more common
http://www.techpowerup.com/reviews/EVGA/GTX_780_Ti_SC_ACX_Cooler/26.html
With such a HUGE difference in prices, quality, and performance on all top-end cards you really have to do your research.
The R9-290X prices vary from $550 to $780 USD!
http://www.techpowerup.com/reviews/EVGA/GTX_780_Ti_SC_ACX_Cooler/26.html
With such a HUGE difference in prices, quality, and performance on all top-end cards you really have to do your research.
The R9-290X prices vary from $550 to $780 USD!
Thanks for the response! I thought I had seen reviews elsewhere that showed the 290 series really closing the gap, or even surpassing the 780ti at higher resolutions, but perhaps I was remembering wrong. I recently decided to upgrade to a dual-290 setup, but if I had gone with a single card, the 780ti was at or near the top of my list (until the 290x prices came crashing down, that is).
See these articles for after-market cooling options:
Air cooling:
http://www.tomshardware.com/reviews/r9-290-accelero-xtreme-290,3671.html
Liquid Cooling:
How to:
http://www.pcper.com/reviews/Graphics-Cards/Using-NZXT-Kraken-G10-Watercool-Radeon-R9-290
And results:
http://www.tomshardware.co.uk/radeon-r9-290-and-290x,review-32872.html
I was more wondering about the value of getting the 290x for $350. I could buy an after market cooler for $50-75. I'm just not sure if it is a worth while upgrade.
For total upgrade worthwhileness ( is that even a word/term? ) what kind of resolution are you going for? Most of the top-end cards are complete overkill if you're not playing above 1080p. If you're not using 1440p or triple displays, I wouldn't bother going above a GTX 770 / R9 280.
I am questioning Toms review about the temps. Temps on Hardwarecanucks are showing something entirely different giving the PCS+ the best temps of all the 290x cards offered. A wooping 63C... even mines have never reach up 67C...
Not to forget the only viable 4k option right now in Crossfire.