Gigabyte GTX 1070 Mini ITX OC
Even the longest can fall short when it comes to mini-ITX enclosures. Suddenly there are other attributes that matter more than just performance, like length, power, and where all of that hot air goes after it's blown off the GPU.
With its GeForce GTX 1070 Mini ITX OC, Gigabyte adapts well to the limitations of small cases, creating a card that's short and still wields Nvidia's powerful GP104 processor. That leaves us with just two questions: how well can the chip be cooled, and how well does Gigabyte manage the trade-off between less surface area and noise output?
This board's price makes it an interesting offering, since Gigabyte deliberately avoids gimmicks and concentrates on the qualities that matter.
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Exterior & Interfaces
The cooler cover is made of black plastic with orange lacquered highlights. Weighing just 605g, this card is a featherweight among the other 1070s. A length of just 6 3/4 in (17.2 cm) also makes the GeForce GTX 1070 Mini ITX OC conveniently short. The height (12.5cm from the upper edge of the motherboard) and depth (3.5cm, the same as most dual-slot cards) are perfectly acceptable.
Gigabyte deliberately doesn't use a continuous single-piece backplate; in ITX projects, thicker structures attached to the back of a card often cause collisions with CPU coolers or memory. The smaller plate at the end of the card shouldn't pose any problems, and it does serve a real purpose.
The top of the card bears an unlit Gigabyte logo, and the eight-pin auxiliary power connector sits at the top's back edge. We can appreciate the simple, yet functional design. Gigabyte even held off on eye-catching lighting, since few mini-ITX enclosures are windowed.
Horizontally-oriented fins direct heated air to the back and front of the card. Accordingly, the slot plate has some openings for ventilation.
You get a total of four display outputs, all of which can be used simultaneously in a multi-monitor setup. In addition to the two dual-link DVI-D connectors, there is also one full-sized HDMI 2.0b port and a DisplayPort 1.4-capable interface.
Board & Components
Gigabyte designed an extra-short PCB for this card. The true art is finding a configuration in which the VRMs are arranged in such a way that potential hot-spots are elegantly avoided, despite the lack of space. In practice, Gigabyte's implementation works well.
Like Nvidia's GeForce GTX 1070 Founders Edition, this card uses eight Samsung K4G80325FB-HC25 modules, each able to store up to 8Gb (32x 256Mb).
Such a short card presents issue with placing the memory. On one hand, distance to the GPU cannot be reduced. On the other, the modules must be kept as far away as possible from the voltage regulation circuitry, else they overheat.
The 4+1-phase system relies on the same uP9511P for PWM control as Nvidia's reference card. Gigabyte places this chip on the back of its PCB, though. The memory's one power phase is controlled by a uP1728 on the top side of the board. The converter rails are doubled, a trick that allows each of them to be advertised as two phases, rather than one. Of course, Gigabyte uses an obligatory INA3221 for monitoring current, too.
Gigabyte implemented a voltage regulation solution that allows it to keep the card short without risking thermal issues. Foxconn coils and 6414 high-side MOSFETs are placed on the front of the PCB, while the five gate drivers responsible for controlling the individual phases are banished to the back.
This is also where the 6508 low-side MOSFETs are found. Two MOSFETs are used for each converter circuit, halving the already low internal resistance of the circuits a second time.
The advantage of this setup is that the low-side MOSFETs can be cooled from above by the cooler, while the low-side chips benefit from increased surface area due to the doubling of MOSFETs. This allows them to be cooled by a small screwed-on plate, preventing problematic hot-spots.
Furthermore, two capacitors are installed right below the GPU to absorb and equalize peaks in voltage.
Before we look at power consumption, we should talk about the correlation between GPU Boost frequency and core voltage, which are so similar that we decided to put their graphs one on top of the other. This also shows that both curves drop as the GPU's temperature rises.
After warming-up in our gaming workload, the GPU Boost frequency fluctuates between 1778 and 1860 MHz. Under a more constant and taxing load, the clock rates drop significantly to a range between 1584 and 1607 MHz.
The voltage measurements respond similarly. While we observe ~0.975V in the beginning, this value later drops as low as 0.893V. It is easy to tell that Gigabyte had to put clock rates on a diet in order to manage power consumption and thermal output.
Combining the measured voltages and currents allows us to derive a total power consumption we can easily confirm with our instrumentation by taking readings at the card's power connectors.
As a result of restrictions imposed by Nvidia, whereby the lowest attainable frequencies are sacrificed to hit higher GPU Boost clock rates, the power consumption of many factory-overclocked cards is disproportionately high when they're idle. Gigabyte achieves a good compromise, though. Its lowest frequency is 164 MHz, only slightly above Nvidia's reference.
|Gaming (Metro Last Light 4K)||155W|
These charts go into more detail on power consumption at idle, during 4K gaming, and under the effects of our stress test. The graphs show how load is distributed between each voltage and supply rail, providing a bird's eye view of load variations and peaks.
Naturally, power consumption directly affects temperatures. The question of how well Gigabyte's compact GeForce GTX 1070 Mini ITX OC copes with thermal energy can only be answered by looking closely at its cooling solution. The company employs two 1/3-inch (8mm) and one 1/4-inch (6mm) heat pipes made of copper-composite material. They make direct contact with the GPU, accelerating dissipation out through the heat sink's fins.
The small plate for cooling the memory modules is seated on an aluminum heat sink. Three heat pipes are embedded in it, and they're directly connected to the finned cooler.
Gigabyte actively cools the six high-side MOSFETs using the cooler's integrated heat sink. It also draws heat from the coils with thermal pads, and applies slight pressure through them to combat vibration, which we come to know as coil noise. This solution kills two birds with one stone; it eliminates hot-spots and noise simultaneously.
The smaller cooling plate on the back covers all 12 low-side MOSFETs and the gate drivers, dissipating excess heat through the back of the card. As you might imagine, this helps with the small board's thermal challenges quite a bit. Registering 151°F (66°C) on an open test bench, and 154°F (68°C) to 156°F (69°C) in a closed case, the GPU's temperatures are completely acceptable.
A relatively high idle temperature between 118°F (48°C) and 122°F (50°C) is attributable to the card's passive mode. Gigabyte's small cooler doesn't really seem suitable for that purpose. In a compact enclosure, we'd suggest keeping the fan spinning at all times, even slowly. Fortunately, this behavior can be adjusted manually through software.
The infrared images reveal no troublesome hot-spots. Nvidia's GPU, Samsung's memory, and the voltage regulators are cooled well, particularly given a dense PCB.
Temperatures rise a bit during our stress test, but they're not high enough to cause concern. The bottom line is that Gigabyte's concept works.
Since the temperatures during our gaming and torture workloads are similar, the observed fan speeds are about the same as well.
There is no start-up peak in the graph, which would normally indicate the jump from passive to active mode. The installed 90mm fan tops out at 3300 RPM and is stable at speeds as low as 400 RPM. As a result, no tricks are necessary to get it up and running. Gigabyte keeps a good grip on hysteresis as well, and that might be helped by the fact that the fan is activated early, just below 132°F (56°C).
Although the 41.8 dB(A) we measure after a prolonged workload isn't particularly quiet, it's also also not loud enough to bother us. Even Nvidia's GeForce GTX Founders Edition is significantly louder. The high-frequency parts of the VRM still generate quantifiable noise, but they're barely audible. Low-frequency buzzing is rather moderate, and the part that actually is measurable is due to airflow.
Gigabyte does a good job with this small card's cooling; it'd be hard for us to suggest significant improvements.