Tiny Radeon R9 Nano to pack a wallop at $650

But AMD's performance numbers may overstate its case

When AMD announced its lineup of graphics cards based on the Fiji GPU, the firm said it would eventually be offering two distinctive products in addition to the Radeon R9 Fury and R9 Fury X. One of those cards will be a dual-GPU monster in the vein of the Radeon R9 295 X2, and the other is an ultra-compact powerhouse known as the Radeon R9 Nano.

Today, AMD is pulling back the curtains on the R9 Nano, revealing a full set of specs and some preliminary performance numbers for this pint-sized overachiever. These cards aren't expected to hit online store shelves until next month, on September 10, but we have quite a bit of info to share today.

The basic appeal of the Nano is its unique combination of power and size. Thanks to a compact physical footprint made possible by HBM and by the Fiji GPU's modest power consumption, the R9 Nano crams Fury-like performance into a card that's just six inches long. AMD says the Nano is well-suited for 4K gaming, and it expects to see Nano-based PCs built around the Mini-ITX standard for compact systems.

Here's a quick look at the Nano's full specs, according to AMD:

The big news here is the fact that the Nano packs a fully enabled Fiji GPU, with the 4096 stream processors and the same 1GHz peak clock speed as the Radeon R9 Fury. The HBM-based memory subsystem has the same 4GB capacity and 512GB/s of bandwidth as the Fury's, too. Although this card is small in stature, its GPU is by no means cut down.

Perhaps the most eye-popping number above is the Nano's typical board power of just 175W. That's fully 100W lower than the R9 Fury's power spec, which is kind of bonkers. And it means the Nano requires only a single eight-pin power input.

AMD says it expects Fury-like performance from the R9 Nano, which may seem like some kind of dark voodoo magic. In reality, though, the Nano likely benefits from one of the most prominent realities in high-performance chips today: in order to eke out the last five to ten percent of performance, one often has raise power consumption dramatically. Power draw is determined by frequency times the square of voltage times the number of transistors cycling. As a result, even a relatively modest decrease in voltage and clock speed can work wonders.

In order to keep power draw in check, AMD has almost surely chosen to run the ultra-wide Fiji engine at somewhat relaxed clocks and voltages. The formula could pay off. The firm claims the R9 Nano is "up to 30% faster" than the Radeon R9 290X while being based on a "40% shorter"board.

I'd be careful not to focus too much on the "up to 1000MHz" clock speed spec in the table above, though. AMD has got to be capping the Nano's power consumption using its PowerTune algorithm, which decides from moment to moment how fast the GPU can run based on a number of inputs, including the GPU workload, temperature, power limit, and so on. As a result, with a 175W limit, the Nano is likely to run at somewhat lower delivered clock speeds than the R9 Fury with its big, beefy cooler and 275W cap.

One of the firm's reps told us the Nano's clock speed will vary according to the workload. For some things, we might see 900MHz. In other cases, the GPU "might even peak to 1000MHz." Nevertheless, AMD projects performance "more or less" like the R9 Fury's. We'll have to get our hands on a card in order to quantify the true meaning of that fuzzy statement.

The Nano's product manager was also careful to dispel the notion that "this card is going to throttle." I'm not sure what "throttling" versus "not throttling" means under the control of a complex algorithm like PowerTune, but the Nano should be well-equipped to keep itself cool under load. The card is expected to have a 75°C typical operating temperature, which AMD points out is 20°C lower than the R9 390X's operating temp.

Cooling duties are handled by a hybrid setup that combines a vapor chamber base with multiple heatpipes snaking into horizonal fins. It's nothing exotic as these things go, but it should suffice for a 175W card. Notably, the Nano's cooling solution has a separate heat pipe and set of fins meant expressly to cool the card's power-delivery circuitry, something the liquid-cooling setup on the Fury X seemed to neglect.

The R9 Nano is claimed to be "library quiet" at 42 dBA, which AMD says is 16 dBA quieter than the R9 290X. Also, unlike the Fury X, the R9 Nano is open for modification by board vendors, so we could see custom versions from the folks at Sapphire, Asus, and so on. AMD tells us some of its partners are prepping designs with water blocks for liquid cooling.

The R9 Nano's distinctive combination of size and competence won't come cheaply, though. AMD says the Nano is a sort of co-flagship with the R9 Fury X, so it has given the Nano the same price: $649.99.

I expect the scarcity of R9 Fury and Fury X cards has something to do with the Nano's healthy price tag. AMD has no reason to ask less if it's selling all of the cards it can produce. The firm says it is "saving up quantities" of the Nano ahead of its launch date in the hopes that the supply will be sufficient to meet demand.

About those performance numbers
Although R9 Nano cards won't be in the hands of reviewers until a later date, AMD has supplied some of its own internal benchmark results comparing the Nano against its closest competition, a mini-ITX version of the GeForce GTX 970. AMD is claiming 30% faster performance than the GTX 970 ITX.

I don't doubt the Nano could outperform the GTX 970, but the results above come with some serious caveats.

You will recall that AMD also released benchmarks for the R9 Fury X ahead of the reviews, and those numbers showed the R9 Fury X consistently beating the GeForce GTX 980 Ti across a range of games. But when we measured the Fury X's performance ourselves, the numbers told a different story:

In the case of 99th-percentile frame times, the story was dramatically different.

The reason for the difference in FPS averages was clear when we looked back at the footnotes of AMD's document supplying the numbers. The firm tested the cards with a very particular formula in order to achieve its results for the Fury X—and it has carried over that formula when generating the R9 Nano results you see above. The basic approach is to test exclusively in 4K with high-quality shader effects and post-process anti-aliasing, but to soft-pedal on texture filtering and mulitsampled edge anti-aliasing. 

Here's how AMD says it tested the games in the Nano benchmark results above, based on the footnotes of its presentation:

MSAA Anisotropic
Battlefield 4 3840x2160 High FXAA 0X 0X
Crysis 3 3840x2160 High - 0X 0X
Far Cry 4 3840x2160 High SMAA 0X 0X
GTA V 3840x2160 High - 0X 4X
Shadow of Mordor 3840x2160 High - 0X 0X
The Witcher 3 3840x2160 High - 0X 0X

That's a pretty weird combination of settings, all things considered. 4K is one of the highest resolutions you can get in a display today, and yet we've compromised dramatically on image quality via low-rent texture filtering and edge AA methods.

Here's a quick illustration of the difference in texture quality between 0X and 16X anisotropic filtering:

Without anisotropic filtering

With 16X anisotropic filtering

The difference in quality between post-process AA methods like SMAA/FXAA and more traditional methods like MSAA isn't quite so dramatic, but post-process AA methods aren't aware of sub-pixel geometry, so they sometimes get things wrong. For example:

FXAA (left) cannot resolve the fine geometry that a sub-pixel-aware technique like MSAA or SSAA can (right)

I can't imagine building a high-end gaming rig, getting a 4K monitor and a fancy video card for it, and then tweaking games to compromise image quality in such basic ways.

So why is AMD testing in this fashion? Probably because it plays to the Fiji GPU's strengths—that enormous shader array—while not leaning so hard on its potential areas of relative weakness, like ROP throughput (for MSAA resolve), texturing (for anisotropic filtering), and small triangles (since polys are relatively smaller at lower resolutions). Taking this peculiar path likely puts the R9 Nano in the best possible competitive light. In the absence of independent reviews, those AMD-provided numbers are sure to circulate widely online. Trouble is, AMD could be setting up the R9 Nano to be a disappointment once it gets into the hands of reviewers and consumers.

So there you have AMD's performance numbers with some proper context. My advice: wait for the reviews before you decide to jump on an R9 Nano. It may well be a very good product. Heck, it looks super-cool. But manufacturer-provided performance numbers often tell a different story than one might hope.

Tags: Graphics

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