While the GTX 970 and GTX 980 undoubtedly deliver on performance, Maxwell is really all about efficiency. Efficient computing means less power consumption and heat output, while still maintaining decent performance. In turn, you can then manage this heat with less bulky and quieter coolers. With its GTX 970 DirectCU Mini, Asus has fully taken advantage of Maxwell’s efficiency, offering one of the world’s most powerful GPUs in a dual-slot card that’s just 170mm long – the same length as a mini-ITX motherboard.
Thankfully, diminished size doesn’t equal diminished build quality. The card comes complete with a lovely metal backplate; it doesn’t offer any direct cooling to components, but it looks better through a window than a bare PCB, and it will still dissipate some heat. The main cooler shroud is formed from plastic, but it’s neither loose nor flimsy.
Meanwhile, the rear I/O panel uses the older Nvidia selection of ports (an extra DVI connection instead of two extra DisplayPort sockets), but it’s still well equipped and includes HDMI 2. Along the top edge you’ll find a single 8-pin PCI-E power connector, with a small LED that changes from red to white to let you know you’ve successfully connected it. There are also two SLI connectors, although we doubt that many people will be using this card in SLI mode – it’s all about getting the most out of a mini-ITX board’s single slot.
Asus has even managed to squeeze a factory overclock onto the card, taking the base clock from 1,050MHz to 1,089MHz (1,228MHz boost). It’s only a 4 per cent increase, but it’s still good to see any overclock on such a small card, although the memory has been left at the stock frequency of 7GHz – you can’t have it all. We’ve seen heavier factory overclocks from both MSI and Galax, but those cards are significantly larger too.
A copper vapour chamber cools the GPU, and a circular array of fins are soldered to this chamber, linking it to an additional metal contact plate that has thermal pads to link it to the vital power circuitry (MOSFETs and VR controller) and the memory chips, although bizarrely only four of the eight dies are directly cooled. Still, there’s clearly a lot of heat being transferred through the DirectCU Mini cooler. On top of the fins is the Asus CoolTech fan, which has an inner radial fan section with outer curved blades, and is designed to push air through the cooler in as many directions as possible while staying quiet. It doesn’t have a semi-passive mode, and exhausts air in all directions through the open sides of the cooler shroud.
Finally, a look at the PCB reveals very efficient use of space. There’s a 4+1 phase power arrangement, for which Asus uses its Super Alloy Power components, which Asus claims offer increased efficiency, less buzzing noise and a longer lifespan. At the time of writing, there’s no waterblock that fits the PCB of this card, which is a shame, as it would be great to see a water-cooled mini-ITX build using this card and the Asus Maximus VII Impact. Hopefully, a manufacturer will seize the opportunity soon.
The 970 Mini’s performance is right where you’d expect it – a few frames per second off the speed of the Galax and MSI GTX 970 cards, which ship with heftier overclocks. You’d be very hard-pressed to notice this difference in actual gameplay though. At 2,560 x 1,440p, in both Battlefield 4 and Crysis 3, the Asus runs comfortably above 30fps with maximum detail (albeit without antialiasing in Crysis 3). With average frame rates of around 40-50fps in these games, the card is ripe for use with a G-Sync screen too. In both of these demanding games, the card is unsuitable for 4K, although you can say the same for any current single-GPU card – even the GTX 980 can’t maintain 20fps in Crysis 3.
BioShock Infinite is our easier test, and the GTX 970 again excels. The Galax and MSI cards, with their higher boosting, have slightly higher frame rates, but the mini Asus card is close behind, with its minimum frame rate never dropping below 60fps at 2,560 x 1,440, and staying at over 30fps at 4K.
The card’s efficiency is also unrivalled. The MSI and Galax cards consume more power than a stock-speed GTX 980, thanks to their high factory overclocks, but with a lower overclock, a single 8-pin header, one fan and smaller power delivery system with efficient components, our entire system drew 264W with the Asus card installed, compared to 409W with a Radeon R9 290X and 309W with the MSI GTX 970.
Overclocking netted some excellent results too. We achieved a whopping 20 per cent overclock, adding 220MHz for a base clock of 1,309MHz. This frequency gave us a boost clock of 1,448MHz, which the Asus card easily hit, sometimes even reaching 1,500MHz or higher. We easily pushed the memory up to 7.8GHz (effective) too.
In our overclocked tests, we see performance improvements of between 13 and 16 per cent, where the Asus closes the gap on MSI and Galax. These two cards are still a touch faster when also overclocked, but the smaller dimensions, power circuitry and cooler certainly don’t appear to be a significant limit on overclocking in this case. There was also no extra noise or much of a temperature increase after overclocking either, and system power consumption amazingly stayed below 300W.
Asus has embraced the efficiency of Maxwell to create a true pocket rocket that’s the perfect companion for a mini-ITX powerhouse. It offers a tremendous amount of power in a small space, and it doesn’t suffer for it either. It might not have a semi-passive mode, but the Asus card still runs quiet and cool, and it overclocks like a champ too. Achieving this feat with the competing AMD R9 290 and R9 290X simply isn’t possible. If you want to squeeze a fast graphics card into a mini-ITX system, the Asus GeForce GTX 970 DirectCU Mini is the perfect card for the job. MATTHEW LAMBERT
SPECIFICATIONS
Graphics processor Nvidia GeForce GTX 970, 1,089MHz (boost 1,228MHz)
Pipeline 1,664 stream processors, 64 ROPs
Memory 4GB GDDR5, 7GHz effective
Bandwidth 224GB/sec
Compatibility DirectX 12, OpenGL 4.5
Outputs/inputs Dual-link DVI-D, Dual-link DVI-I, HDMI, DisplayPort
Power connections 1 x 8-pin, top-mounted
Size 170mm long, dual-slot