Thus, the Gigabyte Radeon HD 6770 Silent Series has the same specs as the reference Radeon HD 6770:
The heatsink of the Silent Cell cooler consists of three parts with four nickel-plated 8mm heat pipes. The cooler’s base is nickel-plated copper, too.
The heatsink has aluminum fins which are 0.25 mm thick and placed 2.5 mm apart from each other. The main heatsink section is pierced with the two central heat pipes whereas the two other sections have one pipe each.
The pipes are flattened out in the cooler’s base and soldered to the latter.
The cooler has contact not only with the GPU but also with the memory chips, via thick thermal pads.
Although not as impressive as the huge cooler from ASUS, the Silent Cell does its job well enough:
The peak temperature of 67°C is quite an achievement for a passive cooler!
The Gigabyte card’s overclocking potential is somewhat lower than the ASUS’s. It was stable at 930/5040 MHz.
Well, that’s not bad for a passively cooled graphics card, especially as the peak GPU temperature increased by a mere 4°C at that, reaching 71°C.
So, the passive cooling systems of the above-discussed Radeon HD 6770s are both highly efficient. Perhaps they are even too efficient for such modest GPUs. Let's see if this is so by installing a small copper heatsink of the Deepcool V4000 cooler on them.
Compared to the original coolers, the ASUS card’s GPU is 12°C hotter (64°C) and the Gigabyte card's GPU is 5°C hotter (72°C). The resulting temperatures are still far from dangerous, though, whereas the Deepcool V4000 heatsink is only half as large as the ASUS DirectCU Silent or the Gigabyte Silent Cell. The fact that the Deepcool heatsink is made from copper may have contributed to its good performance.
We also used the V4000 on a reference ATI Radeon HD 5770 and the latter’s GPU temperature was as high as 81°C.
This indicates that ASUS and Gigabyte select Juniper XT chips capable of working at low voltage and design their PCBs appropriately.