AMD's R9 Nano - Putting Full-Fat Fiji On A Power Diet
During the inaugural PC Gaming Show at E3 2015, AMD took to the stage to present their new Fiji GPU. Based on the latest revision to their GCN microarchitecture, and for the first time featuring High Bandwidth Memory, the design released the following month was the first to incorporate Fiji and allowed AMD to once again go toe-to-toe with NVIDIA’s best.
With the release of the Radeon R9 Fury X the potential of the Fiji GPU package to shrink the size of consumer-class graphics cards was realised, but still held back by the cooling requirements of this new performance silicon, rated in excess of 275W. AMD compromised through the use of an integrated liquid cooler and 120mm radiator, keeping the footprint of the card small whilst also providing excellent cooling for a power-hungry card. The later R9 Fury designs gave board partners the opportunity to create Fiji-based cards with elaborate air-coolers, trading away the size benefit of the new GPU package. The question is, could AMD produce a design which melded the best of both?
The AMD Radeon R9 Nano
Formally unveiled today - with an expected launch in September - is the Radeon R9 Nano, and it’s a considerably different animal to what you might have expected back in July. After the release of the air-cooled R9 Fury, featuring a slightly slimmer Fiji GPU but the same 275W TDP, the expectation was that the R9 Nano would be an even leaner GPU sitting comfortably in the mid-range. This was seen as a necessary step to keep the GPU under control without the benefit of a high-end air cooler or water cooler, but ever coy AMD kept their cards close to their chest. As it turns out, the R9 Nano is a different beast altogether.
First off, the R9 Nano features a full-fat Fiji XT GPU with all 64 Compute Units (4096 shaders) enabled, and yet it maintains the compact ‘mini-ITX’ footprint of the PCB originally floated two months ago. That means that the card is approx. 6-inches long, a full 40% shorter than the flagship reference designs of the 7000 and 200-series GPUs of the past and even more petite than the Fury X; however AMD are claiming performance up to 30% faster than the R9 290X at 4K resolutions. That’s frankly astonishing given it’s only a 175W TDP part.
If these performance figures bear fruit AMD will be bringing new performance levels to the compact mini-ITX PC form factor, as demonstrated by their own Quantum PC project and likely to only gain importance with the release of Steam Machine-based designs from November this year. It will be especially important in designs unable to accommodate a 120mm-radiator (and hence an R9 Fury X), where the NVIDIA GTX 970 Mini or AMD R9 380 Compact were the most appropriate air-cooled alternatives.
Perhaps unsurprisingly therefore AMD are focussing like a laser pointer on the mini-ITX form factor, stating that the R9 Nano is the ‘most performance dense design’ around. However this focus is in of itself a major roll of the dice for AMD. The market for 4K gaming capable true mini-ITX designs - designs which aren’t your typical budget/low-power segment but still can’t accommodate a 120mm radiator - is unproven, but will need to be robust to support a card priced at the same level as the flagship R9 Fury X.
As mentioned, the R9 Nano has a considerably lower TDP than the Fury X, but still ramps up to a 1000MHz engine clock at load (only 50MHz below the Fury X). That seems a counter-intuitive when you consider that the Nano equals the Fury X in both Compute Units and Frame Buffer size, but the key is in the phrase ‘up to’.
All GCN 1.2 architecture cards within AMD's product stack include a ‘power target’ incorporated into the dynamic clocking mechanism of the core engine. Typically this figure has been used to determine any untapped TDP headroom under load, and if so increase the core clocks to make use of it; it’s for this reason that published technical specifications for AMD performance GPUs use the ‘up to’ prefix when describing their core frequency.
The R9 Nano turns this idea on its head somewhat and deliberately limits the power target of the Fiji XT GPU to 175W. As it turns out the Fury X operates in a zone of quite heavy diminishing returns, whereby pushing performance to the bleeding edge pushes up TDP exorbitantly. By dialling back the power target the GPU increases the clock less aggressively, hitting maximum frequencies less often (900Mhz is the typical load frequency) which reduces overall performance, but the performance drop-off nonetheless still places the R9 Nano up to 30% above the R9 290X at 4K. Whilst it’s not quite at Fury/Fury X levels, Nano is still very much a performance part.
Certainly aiding its high resolution capabilities is the use, once again, of High Bandwidth Memory. Sporting the now-familiar compact package on a substrate, the use of HBM has allowed such compact PCBs for the Fury X and now the Nano. The Nano also exploits the energy efficiency of HBM compared to GDDR5 by dedicating more power to the GPU (assuming the same overall system TDP), squeezing just a little more performance out of the card but still hitting the same astonishing memory bandwidth figures seen on the Fury designs.
Overclockers will be pleased to note that overclocking is supported by the R9 Nano, and that the 175W power target is adjustable in Catalyst Control Centre. A word to the wise however – the card is still limited to a single 8-pin PCI-Express power connector and relatively simple 4-phase VRM. Even were you to swap out the cooling to a more effective water-based solution the amount of power that the card can handle safely will be far down on the Fury and Fury X.
Reviews and independent benchmarks for the R9 Nano are still a while away – September 10th is the current anticipated launch date of the card – but AMD have supplied tentative projections based on their own internal testing. These results are all based on performance at 4K (3840*2180) resolutions without anti-aliasing and anisotropic filtering, and are titles which aren’t generally thought to benefit AMD over NVIDIA to any major extent. As always, take them with a pinch of salt.
The fact that the card is up to 30% faster than the 290X is the headline figure, but it’s also worth noting that they claim it can comprehensively trounce the GTX 970 Mini, NVIDIA’s best ITX design and no lightweight itself. Once again however you have to reflect on 4K rendering resolutions tending to benefit disproportionately from the enormous memory bandwidth available via HBM; 1080p and 1440p results may tell a different story. We should also note that these are average frame rates; the in-game experience will depend as much on minimums and how they vary over time.
It’s important to take this fact on board, and so we’ll reiterate it here – AMD expect you to be pairing the R9 Nano with high-resolution panels, not your average 1080p model. Their entire business case for a $650 Nano is contingent on this, which is why the Nano is not a ‘salvaged’ mid-range part using a fraction of Fiji’s available Compute Units.
Reviews for the card are likely to be fascinating. Even if you’re not in the market for a new GPU they’ll be worth a read, as they should show what sort of a trade-off is made when you choose a big core with copious shader numbers over a smaller core clocked to high frequencies.
In order to keep the R9 Nano’s Fiji GPU under control AMD have created a new reference cooler which will come as standard on all launch Nano’s. AMD’s reference cooler woes are well known, and the technical challenges of working within such a compact form factor have necessitated a new approach which dispenses with AMD's traditional designs.
The R9 Nano makes use of a hybrid cooler that incorporates both a large vapour chamber and two heatpipes to cool the GPU and surrounding components. For the first time on an AMD GPU the cooler dedicates one heatpipe and heatsink component to the VRM. The overall solution utilises an axial fan which blow air onto the vapour chamber, exhausting it across the length of the vapour chamber heatsink. Fins are aligned horizontally so some hot air will escape though the rear of the case, but some will still be retained within the chassis. Ensuring that your case is well ventilated, with positive air pressure where possible, will be the best means of achieving consistently low GPU temperatures but will be most difficult in some MITX chassis.
The 90mm diameter fan (with ~86 mm blade coverage) is rated up to 2765 RPM. Such a fan would be able to shift plenty of air, but the noise profile will be an important consideration for anyone assembling an mITX gaming system for the living room, study or bedroom. Small, high RPM fans can tend to be quite shrill, and the tone of this noise rather than amplitude is what causes annoyance but isn't captured in typical sound pressure level (i.e. dBA) figues. Pleasingly fan profiles are configurable in CCC as usual, which will mean that you shouldn’t experience the frequent RPM ramping that can plague similar cooling solutions.
AMD peg the Nano at a ‘library quiet’ 42 dBA, 16dBA quieter than the reference R9 290X. The often variable nature of such tests will make a more complete comparison with existing cards, both reference and 3rd party, quite an interesting read. Like the R9 Fury the Nano has a target temperature of 75C, and will balance fan speed accordingly. Throttling only takes place at 85C, which shouldn’t be a regular occurrence provided the chassis is sufficiently well ventilated.
For launch only the reference design for the R9 Nano will be available. AMD do plan to let their partners do what they do best – create innovative new cooling solutions for their GPUs to best suit their own target market – but these are unlikely to be released in the near future.
As a high-end performance GPU AMD have chosen not to neglect the aesthetics, although the cooler design is slightly more restrictive than that of the Fury X. AMD have opted for a compact cooler with metal shroud that has a brushed aluminium finish, whilst the PCB has a matte black colouration that’s at odds with the glossy black of the Fury X.
The diminutive size and simple lines of the R9 Nano, like the Fury X before it, makes it perfect for showing off if that’s your thing. It’s also small enough for very small mITX chassis, even ones without the 120mm fan emplacement that an R9 Fury X requires, which should serve to unlock yet more compact gaming form factors similar to the AMD Quantum PC project. Expect to see many R9 Nano GPUs mounted parallel to the motherboard in some coming systems due to go on sale soon.
With the exception of raw performance the features of the R9 Nano effectively match those of the R9 Fury and Fury X. The reference design supports three DisplayPort connections and one HDMI 1.4 connection, and is compatible with AMD Eyefinity multi-display setups (up to 6 displays via an external adapter). Due to being HDMI 1.4 rather than 2.0 you’re limited to [email protected] over HDMI, whilst Displayport 1.2 can support the more suitable [email protected] standard.
As you would expect from an AMD GPU the card also supports FreeSync, Virtual Super Resolution and Frame Rate Target Control. Working together with these tools you should be able to tailor performance to any desired level following judicious adjustment of in-game settings, and as a DirectX 12 part the Nano is of course ready to get even more out of the next generation of games.
Finally, the R9 Nano does support up to 4-way Bridgeless CrossFire, so if you want to dispense with the pretence of a tiny mITX system you can assemble some remarkably complex configurations. Indeed the size and TDP of the R9 Nano almost certainly means that it will form a basis for the forthcoming dual-Fiji GPU model due later this year.
Until now performance GPUs have been priced and marketed according to performance, whilst aesthetic features were seen as more of a value-added factor. This trend is well and truly bucked with the Radeon R9 Nano; at an MSRP of $649 AMD are gambling that for a large number of end-users form factor will absolutely trump performance. At that price the R9 Nano ostensibly competes with AMD’s own R9 Fury X and NVIDIA’s GTX 980 Ti, both of which easily surpass it in frame rates and, some would argue, value. The exclusivity and importance that AMD have as a result placed on the Nano is reflected in it being known as a ‘2nd Flagship’, meant to sit alongside the R9 Fury X and cater to a different user base.
It’s certainly true that outside of the R9 Nano truly compact performance GPUs are few and far between, but does this new GPU serve an audience all that far removed from those the R9 Fury X caters to? Certainly while there are multiple Steam Machine chassis concepts which are too restrictive for even the compact dimensions of the Fury X, never mind the 980 Ti, it’s understood that these will be a niche group within a niche rather than mainstream product range. Equally, with 1080p and 1440p benchmarks currently AWOL, is 4K gaming on such a system likely to be widespread? AMD are betting that it will.
The Radeon R9 Nano right now appears to be a pint-sized marvel, but we’ll have a fuller picture when reviews become available.