Nvidia's newest GK104 (Kepler) powered GeForce GTX 670, positioned to go against the HD 7950, is simply a GTX 680 with one of eight SMX units disabled and reduced core clock speed, retaining everything else like the 256-bit GDDR5 memory bus and 32 ROPs. We review GIGABYTE's non-reference take on the new US$399 entrant that really doesn't differ much from their flagship model.
As we can see from this block diagram of the GK104 die, the GTX 670 has one of eight SMX units disabled, which is a common way of putting crocked ASICs that do not meet full binning standards to good use instead of throwing them away. As a result, the GTX 670 has 12.5% less fillrate/pixel pushing performance and lower TDP than the GTX 680, much like how the HD 7950 Tahiti Pro is to the HD 7970 Taihiti XT. Given that everything else remains the same (number of ROPs, memory bus bandwidth, fancy AA algorithms and other technologies), do the loss of shaders really matter for most use cases? We find out in the following pages…
From the onset, we must say that GIGABYTE's GTX 670 OC WindForce 3X 2GB card looks exactly the same as its flagship non-reference GTX 680 model that we've reviewed earlier this year… because it is! Other than a white sticker that identifies it as a GTX 670 over existing silkscreen on the PCB , the card we are looking at today has the same component layout, output connectors and and cooling solution as the top dog, which is a good thing as the old design is engineered for more overclocking headroom and is pin compatible with the
crippled GK104 die anyway.
Unlike the standard GTX 670/GTX 680 design, GIGABYTE's choice pf 8+6 PCIe power inputs allows the card to scale up to 300W of power instead of the anemic 225W.
As we've mentioned earlier, the GTX 670 has a familar board design. 5-phase digital VRMs allows for more power headroom and efficiency while the use of 2oz copper and sensible chokes/capacitors on the PCB ensure uninterrupted gameplay without the chance of things going up in blue smoke.
The Taiwanese TSMC made GK104 Kepler, although not as GP compute friendly (dismal 1/32 DP to FP ratio) as its direct AMD Taihiti competitor, is an efficiency monster when it comes to 3D benchmarks and gaming. Actual frequency headroom varies with voltage and the quality of the ASIC, but generally we should be able to hit 1.2-1.35GHz with conventional cooling and near 2GHz with subzero.
SK-Hynix's 1.5GHz GDDR5 BGA modules makes its way on this board as well, arranged in a 256-bit bus configuration for up to 192GB/s of memory bandwidth.
To take care of the default 170W of TDP, GIGABYTE deployed their "WindForce 3X" direct touch copper heatpipe cooler, which is actually similar in design to the ASUS's DirectCU II (they share the same heatsink OEM, Cooler Master). Each of the three 80mm PWM capable fans are rated up to 0.35A at 12V. There is also a dedicated heatsink for the MOSFETs and the whole cooler is secured to the card by only four screws.