NEW: Gigabyte GTX 1070 G1 Gaming 8G
If there's one thing we've come to expect from Gigabyte's G1 Gaming cards, it's the highest possible performance at a reasonable price. The company's GeForce GTX 1070 G1 Gaming 8G follows that familiar mission with three fans and a fairly bold-looking fan shroud.
Exterior & Interfaces
The fan shroud is made of anthracite-colored matte plastic with decorative orange highlights. Weighing in at a modest 797 grams, the G1 Gaming 8G is a true flyweight. A length of 28.2cm should fit easily in most cases, and a height of 11.5cm is about average. The 3.5cm width is typical of dual-slot designs.
A total of three 80mm fans are meant to ensure the right amount of airflow and pressure. The fact that you can't tell these fans are fairly small is due to the card's proportions, which make it look bigger than it actually is.
The back of the board is covered by a single-piece plate made of what looks like anodized aluminum and adorned with a white Gigabyte logo (there is no back-lighting). This backplate makes it necessary to plan for an extra 5mm of clearance behind the card, which may be relevant in multi-GPU configurations.
Up top, the card is branded with a Gigabyte logo back-lit by an RGB LED. There's also a fan-stop indicator and an eight-pin auxiliary power connector.
A peek at the end and bottom of the GeForce GTX 1070 G1 Gaming 8G reveals that its fins are oriented vertically. They won't allow any waste heat to exhaust out the back. Instead, hot air is pushed from the top and bottom, warming up other components in your case, along with your motherboard underneath. As such, this design decision is rather counterproductive.
The slot plate features five display outputs, of which a maximum of four can be used simultaneously in a multi-monitor setup. In addition to one dual-link DVI-D connector, the bracket also hosts one HDMI 2.0b port and three DisplayPort 1.4-capable interfaces. The rest of the slot plate has openings cut into it, which look like they're meant to help with airflow. In this configuration, however, they're not functional due to Gigabyte's fin design.
Board & Components
Gigabyte's PCB is proprietary with some conservative (yet interesting) component choices.
This card uses eight Samsung K4G80325FB-HC25 modules with a capacity of 8Gb (32x 256Mb). Each chip operates at voltages between 1.305 and 1.597V, depending on the selected clock frequency.
One unique addition is the Holtek HT32F52241 32-bit ARM Cortex-M0+ MCU, which Gigabyte uses for controlling the card's RGB effects.
Gigabyte employs an almost oversized 6+2-phase design, wherein the six GPU phases are supplied by uPI Group's uP9511 eight-phase buck controller.
The GPU's voltage regulation is implemented using one Alpha & Omega AON6508 N-channel AlphaMOS on the low side of each phase and one AON6414A on the high side. What's interesting about these two MOSFETs is the low internal resistance across their performance range, as well as the low control values for the gates. It is thus safe to assume that this choice is an attempt to minimize voltage converter losses.
Gigabyte uses Foxconn's Magic coils, which are fully encapsulated and easy to install during automated assembly.
The memory's two phases are supplied by an unmarked PWM controller, which should roughly correspond to a uP1666 2/1-phase synchronous buck controller. It already comes with an integrated bootstrap Schottky diode and gate driver. The high- and low-side MOSFETs are similar to what we found on the GPU's power phases. Just the coils are slightly smaller.
Current monitoring is handled by a triple-channel Texas Instruments INA3221. Two familiar capacitors are installed right below the GPU to absorb and equalize voltage peaks.
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. Gigabyte uses a power target of ~185W, which in turn causes a relatively frenetic GPU Boost frequency. Short-term drops in clock rate hint that we, at least temporarily, hit the card's power limit.
After a warm-up run through our variable gaming load, the card's GPU Boost clock rate settles at an average 1936 MHz, down from a starting point of 1974 MHz. Under a more constant load, it falls to an average of 1759 MHz.
The voltage measurements look similar. Readings around 1.062V drop to 1.043V as the board's frequency slides.
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. This one can only go as low as 240 MHz. The following table shows what impact that has on our measurements:
|Gaming (Metro Last Light 4K)||180W|
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.
The 3.6A we measure provides lots of margin below the PCI-SIG's 5.5A maximum for a PCIe slot, especially if you're using this card on an older motherboard. Gigabyte only feeds the memory through the PCIe slot; the other six phases are powered through the auxiliary eight-pin connector.
Gigabyte's backplate doesn't play an active role in cooling the GeForce GTX 1070 G1 Gaming 8G. It's mostly aesthetic, though the plate does contribute to the card's structural rigidity.
The built-in, two-stage heat sink for VRM and coils deserves a positive mention. We also like the fact that the memory modules are cooled directly by this simple design's stabilizing frame.
A direct consequence of this simplicity, unfortunately, is an uninspired and cheap-looking thermal solution. It consists of a finned sink with a thick aluminum base plate that also serves as a mount for two 8mm heat pipes in a flattened direct touch configuration. These pipes don't even cover the GPU entirely. They're hardly sufficient for moving excess heat. It would have been more appropriate for Gigabyte to use three heat pipes instead.
Of course, a maximum GPU temperature of 147°F (64°C) keeps this card in the green. But a safe thermal ceiling isn't attributable to the cooler, but rather Gigabyte's very low temperature target. After hitting that ceiling, the fans are audibly hard at work.
Looking at our infrared images, we see that the GPU package (and thus the PCB) is slightly warmer than the cooled GPU itself. A reading of 172°F (78°C) on the voltage converters is also bearable. But that's not surprising given dedicated cooling.
The same holds true when we run our stress test and observe the temperature rising only marginally. This cooler is merely acceptable, since it's already operating at its limit.
Hysteresis is perfectly implemented; there is no annoying on/off/on loop to worry about. However, permanent fan speeds above 2000 RPM are certainly nothing to celebrate, since they're clearly audible.
Although we've heard worse than 38.3 dB(A) under full load, Gigabyte's fans are still significantly louder than many other GeForce GTX 1070s, and unnecessarily so.
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