Power, Temperature, & Noise

As always, last but not least is our look at power, temperature, and noise. Next to price and performance of course, these are some of the most important aspects of a GPU, due in large part to the impact of noise. All things considered, a loud card is undesirable unless there’s a sufficiently good reason – or sufficiently good performance – to ignore the noise.

So far we’ve seen AMD take a lateral when it comes to gaming performance, resulting in R9 285 keeping up with R9 280 rather consistently. It is clear that AMD has specifically intended for R9 285 to deliver R9 280-like gaming performance, so that is exactly what has happened above the hood.

Under the hood however there are not one but two generations of GCN upgrades to account for, which have the potential to significantly alter the power/temp/noise characteristics of the video card. Compared to the GCN 1.0 based Tahiti GPU, GCN 1.2 introduces not only AMD’s radically improved PowerTune implementation, but it also introduces their delta color compression technology that cuts down on the size of the memory bus and the resulting number of RAM chips needed on a completed card. As a result R9 285 can at times perform quite differently from R9 280, especially when it comes to power.

Radeon R9 285 Voltages
Saph. 285 DXOC Load Saph. 285 DXOC Idle AMD R9 280 Load
1.15V 0.9V 1.1V

Starting with voltages, we want to quickly remind everyone that as of GCN 1.1 AMD no longer provides a way of easily reading a GPU’s desired VID, and instead we get the real voltage as reported through the card’s sensors. In this case we’re taking our voltages from LuxMark 2.0, which offers a consistent workload that is strenuous enough to max out the GPU, but light enough that virtually every GPU should be able to boost to its maximum turbo bin. In any case these aren’t going to be the maximum voltages for any given card, but they should be close.

For our Sapphire R9 285 Dual-X OC, we find that our card stabilizes at 1.15V under load and idles at 0.9V. Compared to our R9 280 this appears to be a higher load voltage and idle voltage, but it must be noted that the 280 is reporting its VID instead of its actual voltage.

Meanwhile as GCN 1.2 cards implement the same fine-grained PowerTune support that was first pioneered in GCN 1.1, we want to take a look at average clockspeeds as well. With all of AMD’s modern GCN 1.1+ cards, AMD and most of their partners are advertising the cards by their boost clockspeed. So it’s helpful to see if these cards can maintain these clockspeeds throughout. In practice the potential for throttling is much greater in thermally constrained situations (blowers, e.g. R9 290) than it is for open air coolers, but there is still the potential for hitting situations where we throttle based on power consumption.

Radeon R9 285 Average Clockspeeds
  Saph DXOC (Stock) Saph DXOC (Fact. OC)
Boost Clock 918MHz 965MHz
Metro: LL
918MHz
965MHz
CoH2
918MHz
965MHz
Bioshock
918MHz
963MHz
Battlefield 4
918MHz
965MHz
Crysis 3
918MHz
965MHz
Crysis: Warhead
918MHz
965MHz
TW: Rome 2
918MHz
965MHz
Thief
918MHz
965MHz
GRID 2
918MHz
965MHz

The long and short of it is that the R9 285 Dual-X has no trouble maintaining its 918MHz clockspeed when underclocked. Though it doesn’t affect the averages we do see some very minor fluctuations in clockspeed (an errant 916/917MHz here and there), which is likely due to AMD’s clockspeed governing mechanism rather than any kind of power or temperature throttle. Note that even under FurMark, our worst case (and generally unrealistic) test, the card only falls by less than 20Mhz to 900MHz sustained.

Otherwise if we bring the Dual-X back to its factory overclocked speeds, we find that it has no problem maintaining 965MHz, outside of the exception of Bioshock which fluctuated frequently enough that it averaged a mere 963Mhz.

Unfortunately this means we have also been unable to determine the base clockspeed for these cards. Even holding back cooling and reducing the power target, the R9 285 doesn’t seem to have a GPU clockspeed floor, unlike the Hawaii based R9 290 series.

Idle Power Consumption

At this point outside of cards that are design deficient in some way or another, idle power is unremarkable. Sapphire’s R9 285 Dual-X puts up with the best, with the 2W gain over the R9 280 likely coming from the reduced VRAM capacity.

Load Power Consumption - Crysis 3

Moving on to load power consumption under Crysis 3 we find that power consumption has been reduced compared to the R9 280, but not remarkably so. Despite the much lower official TBP of 190W versus 250W for the R9 280, the actual difference (for virtually equivalent performance) is 13W of savings at the wall. What this tells us is that despite the PowerTune changes, the R9 285 is sustaining power consumption not all that far removed from the R9 280. In practice the R9 280 was unlikely to be drawing near 250W under a gaming workload, so in this case the 190W value for the R9 285 is not all that far removed from the R9 280. The remaining difference is due to the VRAM reduction and some power efficiency gains in Tonga.

On the other hand power consumption for the Dual-X when using its factory overclock launches ahead. The slight increase in performance under Crysis 3 from this overclock will increase the load on the CPU, but only slightly. The rest comes from the power required to hit and sustain the higher clockspeeds of Sapphire’s overclock. As a result we’re looking at power consumption near the level of an R9 280X.

Meanwhile to make a quick GTX 760 comparison, AMD and NVIDIA are virtually tied. At 292W versus 293W, these cards are drawing virtually identical amounts of power. However the GTX 760 ultimately has the efficiency edge, as it delivers better performance under Crysis 3 than the R9 285 does (though in other games the tables could of course turn).

Load Power Consumption - FurMark

Surprisingly, under Furmark the situation is actually reversed. Instead of the R9 285 beating the R9 280, we’re actually seeing it draw 10W more power despite the lower TBP. Though seemingly nonsensical, in practice this is the newer iteration of PowerTune doing a better job of homing in on the card’s 190W limit. This is a situation the coarse PowerTune implementation on R9 280 would have trouble with, causing it to have to back off on clockspeeds much more severely, and ultimately drawing less power than its limit would truly allow.

The end result is something of a wash. The R9 285 is not drawing significantly more or less power than the R9 280, all the while delivering similar performance. In that context we can say that as a result, power efficiency has not meaningfully changed compared to the R9 280.

Finally to make one more GTX 760 comparison, this illustrates that while AMD can generally beat the GTX 760’s performance, it also comes at the cost of maximum power consumption. At least when faced with a worst case scenario, the R9 285 is going to be drawing about 20W more at the wall.

Idle GPU Temperature

When it comes to idle temperatures, Sapphire’s Dual-X cooler is among the best. 30C at idle is average in the pack only because so many other coolers are as equally able at idle.

Load GPU Temperature - Crysis 3

Earlier we mentioned that the Dual-X cooler is probably a bit overpowered for a 190W card, and here we can see why. Under Crysis 3 our card maxes out at a relatively chilly 65C, and even with the factory overclock only pushes to 70C. Sapphire’s card clearly has no problem keeping itself cool.

Load GPU Temperature - FurMark

The greater load from FurMark causes temperatures to rise a bit more, but not exceptionally so. Even under this most strenuous of tests we’re topping out at 70C with reference clockspeeds, or 72C with the factory overclock. So long as Sapphire can hit these temperatures without generating too much noise then they’re golden (or blue, as the case may be).

I would also point out at this time that while the R9 285 Dual-X is significantly cooler than the GTX 760, we’re comparing an open air cooler to a blower. All things considered this is exactly the situation where the open air cooler will be the stronger performer. But it comes at the tradeoff of not being able to directly expel all of its waste heat.

Idle Noise Levels

Much like idle temperatures, idle noise levels are looking quite good for Sapphire’s Dual-X cooler. There are a handful of cards that can drop below even 38.5dB, but at this point we’re quickly approaching the overall noise floor.

Load Noise Levels - Crysis 3

Already doing very well for themselves when it comes to load temperatures, load noise only makes Sapphire’s R9 285 Dual-X look even better. When we underclock it to stock speeds we’re only getting 45.6dB under load, quieter than any Tahiti card, Hawaii card, Pitcairn card, or Kepler card. Only the old GTX 560 Ti (which was impressively overbuilt) can sustain load noises lower than 45.6dB.

Load Noise Levels - FurMark

As was the case with temperatures, FurMark also drives up the load noise levels, but not especially so. Even with this additional heat the R9 285 tops out at 48.3dB, staying comfortably under the 50dB level and trailing only the much less powerful GTX 660 and GTX 560 Ti.

Meanwhile when looking at the R9 285 Dual-X with its factory overclock enabled, we unsurprisingly see an increase in noise from the additional heat generated by the overclock. The total penalty for the overclock is 3-4dB, which is a not-insignificant increase in noise. I feel like Sapphire really hit their sweet spot for balancing noise with performance at stock, so the factory overclock deviates from that some. Overall these noise levels are still well within reason, but they’re now middle of the pack instead of near the head of the pack.

Speaking of Sapphire cards, it’s interesting to compare and contrast the R9 285 with our R9 280, which is also a Sapphire card using an identical cooler. Compared to the R9 280, for the R9 285 Sapphire has found a better balance between temperature and noise. The R9 280 could pull off slightly better temperatures, but it was always above 52dB of noise under load as a result.

Ultimately excluding the vender-specific factors, our look at power, temperature, and noise tells us that much like the R9 285’s gaming performance, the R9 285’s power/temp/noise performance is a lateral move for AMD. Performance hasn’t significantly changed and neither has power, which really helps to distill the essence of R9 285 down to its improved GCN 1.2 feature set. Which in this case in particular means features such as the much finer-grained clockspeeds offered by PowerTune.

Compute Final Thoughts
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  • CrazyElf - Wednesday, September 10, 2014 - link

    All in all, this doesn't really change the market all that much.

    I still very firmly feel that the R9 290 right now (Q3 2014) remains the best price:performance of the mid to high end cards. That and the 4GB VRAM which may make it more future proof.

    What really is interesting at this point is what AMD has to respond on Nvidia's Maxwell.
    Reply
  • MrSpadge - Wednesday, September 10, 2014 - link

    I Agree - Tonga is not bad, but on the other hand it does not change anything substantially compared to Tahiti. This would have been a nice result 1 - 1.5 years after the introduction of Tahiti. But that's almost been 3 years ago! The last time a GPU company showed no real progress after 3 years they went out of business shortly afterwards...

    And seing how AMD brags to beat GTX760 almost makes cry. That's the double cut-down version of a 2.5 years old chip which is significantly smaller than Tonga! This is only a comparison because nVidia kept this card at a far too high price because there was no competitive pressure from AMD.

    If this is all they have their next generation will get stomped by Maxwell.
    Reply
  • iLovefloss - Wednesday, September 10, 2014 - link

    So all you got from this review is that Tonga is a cut down version of Tahiti? After reading this review, this is the impression you were left with? Reply
  • MrSpadge - Thursday, September 11, 2014 - link

    Nope. But in the end the result performs just the same at even almost the same power consumption. Sure, there are some new features.. but so far and I expect for the foreseeable future they don't matter. Reply
  • Demiurge - Wednesday, September 10, 2014 - link

    This is the first mid-range card to have all the value add features of the high-end cards. I wish AMD would leverage TrueAudio better, but the other features and the nice TDP drop.

    The color compression enhancement is a very interesting feature. I think that in itself deserves a little applause because of its significance in the design and comparing to the 280's. I think this is more significant, not as a performance feature, but similar to what Maxwell represented for NV in terms of efficiency. Both are respectable design improvements, in different areas. It's a shame they don't cross-license... seems like such as waste.
    Reply
  • MrSpadge - Thursday, September 11, 2014 - link

    Well, the TDP-drop is real, but mostly saves virtual power. By this I mean that 280 / 7950 never come close to using 250 W, and hence the savings from Tonga are far less than the TDP difference makes it seem. The average between different articles seems to be ~20 W saving at the wall and establishes about a power-efficiency parity with cards like GTX670.

    The color compression could be Tongas best feature. But I still wonder: if Pitcairn on 270X comes so close to 285 and 280 performance with 256 bit memory bus and without color compression.. how much does it really matter (for 285)? To me it seems that Tahiti most often didn't need that large bus rather than color compression working wonders for Tonga. Besides, GTX770 and GTX680 also hold up fine at that performance level with a 256 bit bus.
    Reply
  • Demiurge - Thursday, September 11, 2014 - link

    The TDP drop is something I did not think about being a paper launch value. You make a good point about the color compression too. It will be interesting how both fair. That may be an interesting topic to follow up during the driver refresh.

    As an owner of GTX 260 with a 448-bit bus, I can tell you that with anti-aliasing, it matters quite a bit as that becomes the limiter. The shader count is definitely not the limiter usually in the low-end and mid-range displays that these cards will typically be paired with. My GTX 260 and 1280x1024 monitor kind of illustrate that with 216 Shaders/896MB. :-)

    It isn't pretty, but I don't see anything that forces me to upgrade yet. Think I've got two more generations or so to wait on before performance is significant enough, or a groundbreaking feature would do it. I'm actually considering upgrading out of boredom and interest in gimmicky features more than anything else at this point.
    Reply
  • TiGr1982 - Thursday, September 11, 2014 - link

    GTX 260 is like 6 years old now. It's lacking DX11, having less than 1 GB of (relatively slow) GDDR3 VRAM, and overall should be 3-4 times slower than R9 285 or R9 290, I guess.

    I really didn't think anybody still uses these old gen cards (e.g. I have HD 7950 Boost Dual-X which is essentially identical to R9 280).
    Reply
  • P39Airacobra - Friday, January 09, 2015 - link

    Because they would loose money! LOL. And they are both about the same anyway, Except AMD goes for brute force to get performance,(like using aV8) And Nvidia uses efficency with power. (Like a turbo charged 4cyl or 6cyl) Reply
  • bwat47 - Thursday, September 11, 2014 - link

    "And seing how AMD brags to beat GTX760 almost makes cry. That's the double cut-down version of a 2.5 years old chip which is significantly smaller than Tonga! This is only a comparison because nVidia kept this card at a far too high price because there was no competitive pressure from AMD."

    You are being pretty silly here. Both AMD and Nvidia were rebranding a lot of cards these last few gens. You can'y go after AMD for rebranding a 2-3 year old chip, and then say its fine if nvidia does it and blame AMD's 'lack of competitive pressure'. If lack of competitive pressure was the reason for rebranding, then there was lack of competitive pressure on both sides.

    And I highly doubt the 285 is 'all amd has'. this was just a small update to their product line, to bring some missing features (freesync, true audio etc...), and reduced power consumption to the 28x series. I'm sure there is a 3xx series coming down the road (or whatever they will call it). Both AMD and nvidia have been working been squeezing all they can out of older architecture for the past few years, you can't really put the blame on one of the other without being hypocritical.
    Reply

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