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Review: Asus Strix GTX 960 DirectCU II

by Parm Mann on 22 January 2015, 14:00

Tags: NVIDIA (NASDAQ:NVDA), ASUSTeK (TPE:2357)

Quick Link: HEXUS.net/qacn3o

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Introduction

Which is the best graphics architecture available to PC gamers? That's a fiercely-contested debate at the best of times, but right now, few would argue against the merits of Nvidia's 28nm Maxwell.

With the launch of GeForce GTX 980 and GTX 970 back in September 2014, Maxwell improved high-end performance to a reasonable degree but advanced energy efficiency by a tremendous amount. HEXUS has since put numerous partner cards through the wringer, and the best of the bunch deliver stellar performance in a quiet-running package that consumes far less power than any competing solution.

It's easy to sing Maxwell's praises, but there is an obvious problem: GTX 970 pricing starts at £260 and rises to over £400 for the range-topping GTX 980. Sure, they're great parts, but not everyone can afford to lavish such sums on a GPU upgrade.

The sweet spot for mainstream gamers is reckoned to be around the £150 - £200 price point and Nvidia is today filling that void by extending the reach of Maxwell with a third-rung solution priced from £159.99 and dubbed GeForce GTX 960.

The GM206 GPU

In order to make the GTX 960 a reality, Nvidia has created a purpose-built Maxwell GPU codenamed GM206. Tailored to reduce manufacturing cost, the 28nm die measures 227mm², packs 2.9 billion transistors and carries across a lot of what's good about the GM204 featured in both GTX 980 and GTX 970.

Taking a high-level overview, we can see that GM206 features just the two graphics processing clusters (GPCs) - half of what's available to GTX 980 - and each is home to four SMM units. 128 cores per SMM gives GM206 a total of 1,024 processors, and what's interesting is that this is the full implementation of GM206. If there is to be a subsequent GTX 960 Ti, it'll most likely take the form of a dialled-down GM204.

All the efficiency enhancements on existing Maxwell parts are present and accounted for - including 96KB of dedicated memory per SMM unit - and as we already know, each GM206 core claims to offer 1.4x the performance of previous-generation Kepler (GK106). According to Nvidia, then, the 1,024 processors on offer here are theoretically equivalent to 1,434 processors on a GTX 700-series card.

Maxwell Economised

The big question mark surrounding any x60-series part is exactly how much performance has been sacrificed in order to meet the lower price point? In the case of GTX 960, the numbers don't paint a particularly pretty picture. Compared to next-in-line GTX 970, the number of processors has been reduced from 1,664 to 1,024 (down 38 per cent), the number of texture units falls from 104 to 65 (also down 38 per cent) while ROP count has been cut in half, from 64 to 32.

Confounding matters, there are equally drastic cutbacks to the backend. The GTX 960 memory bus has been narrowed to 128 bits, and the GPU is partnered with just 2GB of 7,012MHz GDDR5 memory, resulting in a memory bandwidth of 112GB/s.

GeForce
GTX 960 (2GB)
Launch date
September 2014
September 2014
January 2015
June 2013
September 2012
May 2011
Codename
GM204
GM204
GM206
GK104
GK106
GK114
Architecture
28nm Maxwell
28nm Maxwell
28nm Maxwell
28nm Kepler
28nm Kepler
40nm Fermi
Transistors (billion)
5.2
5.2
2.9
3.5
2.5
2.0
Die Size (mm²)
398
398
227
294
221
367
SM Units
16
13
8
6
5
7
Cores
2,048
1,664
1,024
1,152
960
336
Texture Units
128
104
64
96
80
56
ROP Units
64
64
32
32
24
32
Base Clock (MHz)
1,127
1,050
1,126
980
980
810
Boost Clock (MHz)
1,216
1,178
1,178
1,033
1,033
N/A
Peak GFLOPS
4,981
3,920
2,413
2,258
1,882
1,089
Memory Clock (MHz)
7,012
7,012
7,012
6,008
6,008
4,008
Memory Bus (bits)
256
256
128
256
192
256
Bandwidth (GB/s)
224
224
112
192
144
128
Power Connectors
6+6
6+6
6
6+6
6
6+6
TDP (watts)
165
145
120
170
140
150
GFLOPS per watt
30.2
27.0
19.2
13.3
13.4
7.4
US Launch Price
$549
$329
$199
$249
$199
$199

Perusing the specification table with bewilderment? We don't blame you: on paper, the GTX 960 looks strangely hamstrung. There are fewer cores and texture units than the previous-generation GTX 760, and 2GB of memory fed via a 128-bit bus seems a significant limitation on a modern-day, mid-range card.

But if Maxwell has taught us anything, it's that more isn't always better, and efficiency is key. Much like the CPU landscape, today's GPUs are attempting to marginally improve performance while drastically reducing power consumption. To that end, Nvidia is keen to highlight the architectural upgrades available to Maxwell. We've covered the changes in greater detail in our original GTX 980 review, but the memory enhancements are worth repeating.

As you may recall, Nvidia makes use of a third-generation delta colour-compression engine that, when combined with an improved on-chip cache, lets Maxwell GPUs reduce the size of memory transactions and make more efficient use of bandwidth. According to Nvidia, the Maxwell memory architecture is 33 per cent more efficient than Kepler, which in theory implies an effective GTX 960 memory bandwidth of 149MB/s. Even so, we wouldn't expect GTX 960 to be significantly faster than GTX 760 in modern games, and in titles with higher memory demands we'd be surprised if it's faster at all.

Who's It For?

We're getting buried beneath the numbers so let's change direction by contemplating who the GTX 960 is aimed at. Nvidia's specification isn't exactly geared toward gaming enthusiasts, however there are a couple of key points that will appeal to certain users.

Firstly, there's the 120W TDP, which if memory serves is the lowest we've ever seen on an x60-series card. Only a single six-pin PCIe power connector is required, and given the GPU's low-power credentials, we should see partner designs that are practically silent when idle and extremely quiet under load.

The ideal GPU for a HTPC, then? Perhaps, and Nvidia certainly thinks so, as the GM206 chip features one new feature that even GM204 doesn't have: support for H.265 encoding and decoding. Both GTX 980 and GTX 970 support encode only, giving GTX 960 an upper hand in terms of multimedia duties.

Secondly, we're told that GeForce GTX 960 has "a tremendous amount of headroom for overclocking." Nvidia reckons GM206 will hit speeds of 1,450MHz or more with only air cooling, making the default 1,178MHz boost clock appear particularly conservative.

HTPC aficionados and overclockers may therefore be receptive to what GTX 960 has to offer, but the real target audience is gamers on older GPUs. According to Nvidia, two thirds of GeForce gamers in this 'sweet spot' class are using a GTX 660 or something older, and said users are being presented with an obvious upgrade path.

GeForce GTX 960 claims to be 50 per cent faster than GTX 660, and if you're no longer able to maintain a consistent 60 frames per second at 1080p with maximum image quality, here's an affordable card that offers all the latest Nvidia technologies and DX12 support in an efficient overall package. Worthy of consideration? Let's put a partner card through its paces and see.