The desire to find the sweet spot runs deep within the enthusiast community. Predictably, then, we spend a lot of our time seeking out the best possible values here at TR. For motherboards, the middle of the pack is usually where it's at. High-end boards are rarely faster than their mid-range counterparts, and they seldom offer dramatically different feature sets. The fact there are so many good enthusiast-oriented boards at around $150 only further fuels cynicism toward mobos well north of the $200 mark.
Still, beneath even my growing crotchety old-manness lies a juvenile lust for over-the-top excess. I love finding that perfect value when it's time to spend my own money, but I'm just as interested to see what can be done when cost constraints aren't so tight. Besides, uber mobos typically debut new features and capabilities that will eventually trickle down to the more affordable ones.
Our latest look at bleeding-edge motherboards focuses on AMD's 890FX chipset, which serves as a launch vehicle of sorts for the new six-core Phenom II X6 1090T. At around $300 online, the hexa-core CPU formerly known as Thuban isn't the same class of processor as Intel's thousand-dollar-plus Core i7-980X. High-end 890FX boards are considerably cheaper than their Intel-based equivalents, too. Of the three flagships we've gathered from Asus, Gigabyte, and MSI, not one costs more than $250. Premium P55 and X58 boards, by contrast, regularly sell for between $300 and $400.
Don't think these 890FX boards cut corners, though. Asus' Crosshair IV Formula is loaded with all sorts of Republic of Gamers goodness. Gigabyte's 890FXA-UD7 has a whopping six PCI Express x16 slots. And MSI's 890FXA-GD70 has electrical components that meet military standards. High-end excess all around.
The key to all of these boards is a pair of chips known collectively as the 890FX chipset. The newest element in this core-logic tag team is its RD890 component. This chip has a HyperTransport 3.0 processor interface that's compatible with a wide range of past and present AMD CPUs. The RD890 also features an Input/Output Memory Management Unit (IOMMU) that gives system devices access to virtual memory addressing. AMD says this feature can improve performance in virtualized environments by allowing devices to use their native drivers. The IOMMU is exclusive to the 890FX and unavailable on AMD's other 800-series chipsets.
Otherwise, the RD890 is a massive PCI Express hub. The chip offers 42 PCIe lanes spread across 11 PCIe "engines." 32 lanes are reserved for graphics cards and can be split into a dual-x16 config or a four-way-x8 setup, allowing for all sorts of CrossFire flexibility. Of the remaining 10 lanes, four are reserved for a single x4 connection, while six are available as separate x1 links.
Besides being the answer to life, the universe, and everything, 42 also happens to be the exact same number of PCIe lanes available in the old 790FXnot that the 890FX needs more. The natural competition, Intel's X58 Express, offers only 36 lanes of second-gen PCI Express.
The RD890 bandwidth bandwagon doesn't stop there. The chip features a four-lane A-Link interconnect to the south bridge with 4GB/s of bidirectional bandwidthdouble the throughput of Intel's DMI interconnect. The A-Link interconnect seems to be a collection of thinly disguised, dedicated PCI Express Gen2 lanes, for what it's worth.
The SB850 south bridge first arrived a couple of months ago as part of AMD's jack-of-all-trades 890GX chipset. This all-new chip is a big improvement over the SB750, whose roots can be traced all the way back to the notoriously problematic SB600. The SB850 sports a couple of PCI Express lanes for expansion devices, and those run at a full Gen2 rate of 5GT/s, unlike the 5-series Intel chipsets stuck at half that. Happily, motherboard makers shouldn't have to resort to PCIe bridge chips to ensure sufficient bandwidth for auxiliary USB 3.0 and SATA 6Gbps controllers.
Of course, the SB850 doesn't need outside help on the SATA front. The chip has a six-port, 6Gbps Serial ATA controller of AMD's own design. All the usual RAID configurations are supported, making this the most complete and up-to-date storage controller you can find in a core-logic chipset. Lest you think AMD's forgotten the stubborn few who are still hanging onto IDE burners, the SB850 includes an old-school ATA controller, too.
The SB850's USB logic isn't quite so progressive: it offers 14 ports at 2.0 speeds. The company says 6Gbps SATA support was a higher priority, which strikes me as a little odd considering users are more likely to benefit from a faster USB interface. Not even the current crop of crazy-fast SSDs can sustain transfer rates high enough to saturate 3Gbps SATA, but just about everyone these days has a 2.5" external hard drive that can easily exceed USB 2.0 speeds.
On the networking front, the SB850 has a Gigabit Ethernet MAC that most mobo makers will probably ignore in favor of discrete networking controllers from Realtek and the like. Throw in PCI and HD audio interfaces, and that pretty much sums up the SB850.
TSMC fabricates both elements of the 890FX on a 65-nano process. The RD890 has a maximum TDP rating of 9.6W, while the SB850 has a 6W TDP. For reference, the 890GX, which has 22 PCIe lanes and an integrated Radeon, has a TDP of 25W.
The 890FX three ways
We'll dive into much greater detail on each motherboard in a moment, but first, let's see how they stack up side by side.
|Asus Crosshair IV Formula||Gigabyte 890FXA-UD7||MSI 890FXA-GD70|
4 PCIe x16
6 PCIe x16
5 PCIe x16
1 PCIe x1
|Gigabit Ethernet||Marvell 88E8059||2 x Realtek RTL8111D||2 x Realtek RTL8111DL|
|Auxiliary SATA||JMicron JMB363||Gigabyte GSATA2||JMicron JMB363|
|USB 3.0||NEC D720200F1||NEC D720200F1||NEC D720200F1|
Creative SupremeFX X-Fi
|Realtek ALC889||Realtek ALC889|
|FireWire||VIA VT6315N||Texas Instruments TSB42AB23||VIA VT6315N|
|Warranty length||Three years||Three years||Three years|
The MSI board's lower price tag suggests it might be the most subdued of the bunch, but the GD70 certainly isn't lacking for expansion slots and integrated peripherals. It is working with half the number of CPU power phases as the other boards, although it still has enough juice to feed a six-core Phenom II.
The Asus and Gigabyte boards ring in a good $30 and $50 more than the MSI. Neither offers substantially more slots or integrated peripherals, but there are hints about where the extra money went. The Crosshair, for example, comes with Creative SupremeFX X-Fi software that piles all sorts of 3D audio goodness on top of a vanilla Via codec. The Gigabyte, well, it's the first desktop board we've seen with a cool half-dozen PCI Express x16 slots.