Quad-SLI: Something You Need To Plan Out
I'm pretty gosh-darned convinced that the most sensible application for dual-GPU boards is now quad-GPU configurations. If you're not running four GPUs, put a couple of single-GPU cards in CrossFire or SLI, spend less money, and avoid dumping gratuitous heat into your chassis. It's as simple as that.
Should you decide to take the plunge, though, and pursue unbridled performance via four graphics processors operating concurrently, there are precautions that need to be taken (especially when you're talking about these specific designs with mid-mounted fans).
Ahead of the Radeon HD 6990 launch, AMD gave no indication of what it'd take to properly support a pair of Antilles boards in four-way CrossFire. Even now, you can hit the 6990's product page and find very little detail on what you need to enjoy a trouble-free experience. That is a mistake, in my opinion, because you cannot drop 750 W worth of graphics cards into any platform with the slots to spare and expect them to run well. You need the right power supply, the right motherboard, and most of all, the right enclosure. Certain cases simply cannot cope with volume of heated air that gets recirculated.
Nvidia addresses the need for more information with its own list of validated components. And while we don't necessarily like the limited number of options resident on those lists (especially the very short group of chassis that get a nod), I'm more comfortable with slim pickings than a dice roll.
If you plan to build using two GeForce GTX 590s, here are the lists of approved components as they exist thus far:
Perhaps the most important quality to look for in a motherboard is proper slot spacing. Whether you're in the market for two GTX 590s or a pair of HD 6990s, there needs to be at least one vacant slot worth of space between the cards. The following list is composed of platforms approved by Nvidia to support dual GeForce GTX 590s.
All of these models might work well thermally, mechanically, and acoustically, but I'd also want to conduct extra tests to determine if splitting 16 lanes of aggregate PCI Express connectivity between four GPUs on those P67- and P55-based boards yields acceptable scaling. All of our single-card testing was done on an X58 board. However, the system we used for benchmarking SLI'd and CrossFire'd configs centers on P67.
|Intel X58 Express||Asus P6T7 WS Supercomputer|
|Asus Rampage III Extreme|
|Asus Rampage III Formula|
|Evga X58 FTW3|
|MSI X58 Pro-E|
|Intel P67 Express||Asus P8P67 Deluxe|
|Asus P8P67 Pro|
|Asus P8P67 WS Revolution|
|Asus Sabertooth P67|
|Intel P55 Express||Asus Maximus III Extreme|
|DFI LANParty DK P55-T3EH9|
|Evga P55 FTW 200|
|MSI Big Bang Trinergy|
Quad-Approved Power Supplies
The principle concern when it comes to power delivery is making sure you have enough sustainable output. Nvidia's list of recommendations incorporates 1100+ W models with at least four eight-pin auxiliary power connectors.
|Quad-SLI-Approved Power Supplies|
|Nexus RX-1.1K Gold|
|Thermaltake Toughpower 1500 W|
|AcBel PC8055 1100 W|
Obviously, ventilation and physical orientation are both factors that have to be addressed in case choice. There are a lot of really nice-looking enclosures out there simply unable to cope with two 365 or 375 W graphics cards recirculating half of their dissipated heat. Currently, the list of validated enclosures is dismally-short. Hope you like one of these three options!
|Cooler Master HAF X|
|Thermaltake Element V|
|SilverStone Raven RV02|
Of course, we really shouldn't be complaining, as we still haven't seen any recommendations from AMD.
Assuming the DiY market for quad-GPU-based setups is miniscule, this is really more guidance for system builders than anything. We've been in contact with a couple different boutique folks through the past two launches, just trying to get a sense for what they think about working around these super-hot dual-GPU offerings. This time, we got extra lucky and scored the fruits of one company's pre-launch efforts...