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AMD Radeon R9 285 Review: Tonga and GCN Update 3.0

On paper, the new Tonga-based R9 285 looks to be slightly slower than the R9 280 it is intended to replace, but there's more than meets the eye.

Temperature and Noise Results

Temperatures during Continuous Operation

Lower power consumption should result in lower GPU temperatures under load, which, in turn, should lead to a simpler and quieter cooling solution. It sounds good in theory, but let’s take a look at how the Gigabyte R9 285 WindForce OC actually handles heat.

Infrared Measurements with the Optris PI450

Interestingly, we’ve identified a method to confirm what our sensors tell us in the form of the PI450 by Optris. This piece of equipment 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.

Warmup Process with Pictures, Video, and Numbers

The ambient temperature was 22 degrees Celsius during all measurements. On the open bench table, the Gigabyte R9 285 WindForce OC comes in at 29 degrees Celsius at idle, 64 degrees Celsius during gaming, and 65-66 degrees Celsius during the stress test.

It’s plain to see that, even under a constant load, the only area that really heats up is around the voltage converters. The cooler’s surface comes in at 72 degrees Celsius, which is definitely acceptable.

Things don’t look as pretty when turning the graphics card around. Low fan RPM are certainly nicer to listen to, but they’re not so great when it comes to cooling the voltage converters. It’s a pretty safe bet that the back of the board gets just as hot as the components on the front after the warmup phase. Consequently, the almost 90 degrees Celsius measured at the area on the back of the board that has the voltage converters on the front are a realistic result.

This doesn’t cause any damage, of course, since the board and all active components involved are designed for high temperatures like these. Then again, we also see how the temperatures spread across the board to areas where the connectors of sensitive components have been permanently soldered to the board. We’ve illustrated the whole process with our 2-minute (originally 20-minute) time-lapse video.

Incidentally, this finding isn’t unique to the Gigabyte R9 285 WindForce OC. All current high-end graphics cards’ boards get excessively hot. A backplate doesn’t help either and might well be counterproductive. The table below provides a summary of all temperature results.

Idle3D Workload - Open Benchtable3D Workload -  Closed Case
Gigabyte R9 285 Windforce OC29 °C64 °C66-67 °C
Gigabyte R9 280X Windforce30 °C73 °C75 °C

Noise Measurement

Graphics cards’ noise measurements are performed using a calibrated high-end studio microphone (supercardioid) positioned perpendicular to the middle of the graphics card in question at a distance of 50 cm. This distance, in conjunction with the very strong cardioid directionality of the microphone, represents a compromise between avoiding noise due to fan turbulence and avoiding ambient noise, which can never be completely eliminated. We performed all of the noise measurements at night for this reason.

We’ve also used a closed case to simulate everyday-life conditions. After the warmup phase, we don’t just measure the temperatures, but also the fans’ RPM. We then manually set the fans’ RPM to these values after shifting to the open setup. Doing it this way allows for real comparison measurements under identical acoustic conditions.

So how does the Gigabyte R9 285 WindForce OC fare when it comes to noise? Pretty well, actually.

This is what the cold hard numbers look like:

Idle3D Workload - Open Benchtable3D Workload -  Closed Case
Gigabyte R9 285 Windforce OC30.9 dB(A)35.5 dB(A)36.8 dB(A)
Gigabyte R9 280X Windforce31.4 dB(A)42.7 dB(A)44.9 dB(A)

We also captured a few more load noise comparison data points in our Canadian labs. These were performed in an open case environment, from 3" behind the output bezel of the graphics cards, after 10 minutes of Battlefield 4: 

While the Radeon HD 7870 reference card is the loudest, all of these cards deliver acceptable acoustic performance. Having said that, Asus' Strix Radeon R9 285 stands out as extra quiet in this particular comparison.