This card’s been a long time coming, as MSI has had the 7970 Lightning on the market for a few months now, and AMD’s even launched the GHz edition. Then again, as they say - good things are worth waiting for.
GIGABYTE has developed not only a custom PCB for the new HD7970 SOC, but has also gone to work on the cooler, featuring the "world's first five fan design" and a triple slot heatsink that brings the card’s total weight to a hefty 1596 grams. At first we weren't too sure of the five fan design, thinking of a whole mess of alternative options; or, more specifically, how we would have done things differently.
To be honest though, given performance of the design GIGABYTE has came up with, it couldn't have been made much better. The first apparent ‘flaw’ most people pick up on, just glancing at the card, are the outwards facing fans. That is, they are ‘pulling’ air through the GPU block instead of ‘pushing’, which is usually the most efficient cooling method.
The reason Gigabyte chose to pull air was to stop hot air pockets forming underneath the card, in-between the motherboard and the heatsink. In order to stop that, GIGABYTE’s had to make a choice: either set the fans to pull, and sit them on top of the card as it has done, or use them in push mode and mount them on the bottom of the heatsink near the PCI slot. However, there’s very limited room, and that option would likely have impacted airflow more severely than the choice GIGABYTE finally went with.
Given the rather enormous four-piped vapour chamber, this card’s heatsink can dissipate an enormous amount of heat. Running the standard 1080MHz core clock on this card, the AMD reference heatsink would be sitting on roughly 85C, if not higher. GIGABYTE’s design managed to keep the card under 64C while benching at these clocks, and even cooler when playing less demanding games like Heroes of Newerth or League of Legends; around 53C, in fact.
Idle temperatures were very comfortable, sitting on 36C with the fans not making more than a small whisper. Using software, we were actually able to turn the fans completely off, and the temperature never went above 48C while running 2D applications and web browsing. The fans can then be set up to kick in when the temperature reaches a user determined threshold, so there is no risk of overheating due to forgetting to re-enable fans.
When gaming using the stock clocks, stock fan profile, and an open air test bench we could only barely hear the 7970 spin up under load. Inside a case you just won’t hear it, especially not over other fans inside a typical PC case. If you do find the fans slightly too loud, however, given the enormity of this heatsink you can happily turn the fan RPM down to a level that better suits you, and the card will still run well below dangerous temperatures. We were surprised, but these fans aren't actually that loud.
If we take a look at the PCB we see five Proadlizer chips from NEC. What these essentially do is replace some capacitors and allow for greater current storage with a lower physical space requirement. When we spoke to GIGABYTE about the inclusion of five chips, it stated the original design came with four, which was more than enough, but due to some early testers’ feedback GIGABYTE included a fifth, as the cost of manufacturing barely changed and it’s possible that under the most extreme uses (LN2 and heavy modifications) the card may actually be able to make use of it.