A Closer Look Part II
In the picture below we see the additional PCB that MSI calls the GPU Reactor. It connects to small headers adjacent to the GPU. Its function is to supply clean and filtered voltage to the GPU with the aim of minimizing ripple. This feature is obviously designed to maximize overclocking and further emphasizes MSI's focus on providing a real enthusiasts card, both as a stock air cooled card as well as catering to the ln2 cooling crowd.
The module is lit with blue LEDs and will be quite prominent in a windowed case. Do be aware that the protruding module could potentially interfere with some large CPU coolers and/or motherboard heatsinks. The same applies to SLI configurations. Running a pair of these in SLI will effectively require three slots between the first and second cards.
Previous Lightning cards have featured Proadlizer capacitors for a similar purpose. The GPU reactor takes this design feature to the next level. The card is simply begging to have extra voltage added to it. Running a card like this at stock voltage simply makes no sense and gives the finger to Nvidia's imposed 1.175v limit.
In the pic below we see the three cables that connect to the small voltage reading plugs. They are used measure the core, memory and PLL voltages when connected to a digital multimeter, hence the triple overvoltage moniker.
We also have a good view of the fans of the Twin Frozr IV cooler. A primary design feature of these fans is the ability to spin backwards for about 30 seconds at high speed. The purpose is to avoid dust buildup. Don't worry when powering it on for the first time. The fans really aren't that loud. By the time windows loads, the fans will already be spinning down to their regular levels.
Also note the slight protrusion of the fans. As they are not flush to the metal shroud, it makes it effectively impossible to run in SLI when sandwiched tightly together. When combined with the protruding GPU reactor, the cards can basically be considered as triple slot cards.
As we'll see later on, the Twin Frozr IV cooler does an excellent job, keeping the card very cool while maintaining low noise levels in most reasonable usage scenarios. There are a total of five nickel plated heatpipes. Two are of a large 8mm width that distribute heat to the furthest parts of the heatsink. The cooler hasn't changed much from previous Twin Frozr iterations, but then when it works this well, there's no need to change it.
The card prominently features components that pass military standard qualification testing. We have a very robust 12 phase PWM system, Hi-C Caps, copper mosfets and pretty nice looking gold plated chokes. We also see the twin 8-pin PCIe power connectors on the far right. Besides providing greatly enhanced power delivery capabilities, this means the cards components have the bonus of a greatly extended expected lifetime. The metal shroud that covers the pcb has the dual benefit of providing cooling for the memory chips and mosfets as well as adding a great deal of rigidity to the card.
In the top middle we see the small BIOS selection switch. As we briefly mentioned, the LN2 BIOS disables the protection mechanisms that can be a hindrance when overclocking with sub zero cooling. Phase switching and overcurrent protection are disabled when using this BIOS. This, along with a much higher TDP limit of 300% are major highlights for the LN2 overclockers. MSI claims that using by using this BIOS, up to 900w of power can be delivered! Features like this usually involve hard modifications so it is great to see MSI embracing the overclocking community by providing these options with a simple flick of a switch.
A CHiL semiconductor CHL8318 PWM performs most of the voltage control functions. This chip is i2C controllable and is found on several other GTX 680 models, however for whatever reason, Nvidia do not allow this. MSI have risked the wrath of Nvidia by allowing software voltage control, although this may be coming to an end sooner rather than later thanks to some high level phone calls. An enterprising user will still be able to do this thanks to BIOSes floating around in the wild. So if you buy a 680 Lightning in the future, you may still use the software voltage control by flashing to one of these unlocked BIOSes.