The support metal bracket
Removing the cooler, we find that a metal bracket supports the card and is screwed to the IO plate. The bracket keeps the lengthy graphics card rigid so that it doesn’t flex under the weight of the Twin Frozr III cooler. The card still sagged when installed but the much of the strain was removed. The metal plate also provides additional cooling to the components and come pre-installed with thermal pads.
Dismantling the Lightning
Taking the card apart leaves us with the bare PCB, the metal bracket, the heatsink and fans, and the shroud.
The heatsink and fans
The Twin Frozr III cooler uses a lower profile heatsink made up of 58 densely packed aluminium fins and two 9cm fans. These provide enough surface area for efficient heat dissipation. The fans have PWM functionality and both are connected via a single 4 pin header on the PCB. One downside of the cooling system is that cool air is pushed towards the PCB rather than directed to the back of the case, as with the reference design.
The dense fin array
From the underside, we can see that the fins are laminar and the 5 copper heat pipes are distributed across the heatsink to transfer heat over a larger area.
The copper base and heat pipes
The base uses a nickel plated copper construction for better heat conductivity from the GPU core. All 5 heat pipes originate from the base.
The Cayman GPU
The Cayman core seen here has a die size of 389 mm squared, significantly larger than the 255mm squared Barts core and the 334mm squared Cypress core. This is the largest AMD core since the notorious R600 core design which came at 420 mm squared. The fabrication is still on the 40nm process due to the lack of readily available 32nm or 28nm manufacturing.
The memory modules
The memory modules are once again GDDR5 chips sourced from Hynix rather than Samsung. The H5GQ 2H24MFR RoC 047A chips operate at 1.5V. The R0 denotes that the memory is rated at 6GHz, superior to the modules used on the HD6950. The same modules are used on the reference HD6970 boards. Each module is 256MB to give a total of 2GB of VRAM.
The power circuitry
The MSI HD6970 Lightning features an 18 phase PWM power circuitry as signified by the 18 super ferrite chokes. That’s 10 more than the reference design. Furthermore, the chokes are superior to standard ones and provide greater current capacity and efficiency. The three chokes near the end of the PCB are reserved for the memory. The MOSFETs linked to the chokes have built in copper heatspreaders for additional cooling compared to standard designs. The metal bracket is still used for good measure and to dissipate the heat away.
The integrated voltage controllers
The card uses two voltage controllers to allow software voltage adjustments. As expected, MSI’s own Afterburner program has support for voltage tweaking and more uniquely, the memory voltage and auxiliary voltages can also be controlled.
MSI R6970 Lightning PCB VS reference HD6970 PCB
The actual PCB doesn’t span the whole 31cm length of the card. Instead it measures 28.3, nearly a centimetre longer than the reference PCB placed next to it. The extra length of the card is due to the cooler shroud overhanging the PCB. The layouts of both boards are very similar but the more robust circuitry of the Lightning doesn’t have to be pointed out.
