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Asus' A8N32-SLI Deluxe motherboard

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ModelA8N32-SLI Deluxe
Price (Street)

NVIDIA'S NFORCE4 SLI chipset has been out for about a year now, so it's due for a refresh. That refresh comes in the form of the nForce4 SLI X16, a new chipset that addresses one of the main criticisms of the original nForce4 SLI: the fact that it only provides eight lanes of PCI Express to each graphics card in SLI. The new SLI X16 chipset provides—you guessed it—16 lanes of PCI Express to each graphics card in SLI, with enough lanes to spare for additional PCI-E slots and peripherals. Support for RAID 5 has also been added to the nForce4 SLI chipset for the new X16 edition, bringing NVIDIA's K8 platform up to feature parity with its Intel Edition chipset.

Asus' A8N32-SLI Deluxe is the first nForce4 SLI X16-based Athlon 64 motherboard to hit the market, and it's more than just a simple refresh of Asus' nForce4 SLI design. The A8N32-SLI is equipped with a swanky new heat pipe cooler that keeps its VRMs and chipset cool without making a sound. It's also loaded with extra peripherals and eight-phase power. Oh, and it overclocks like mad, too. Read on for more on NVIDIA's nForce4 SLI X16 chipset and Asus' excellent implementation in the A8N32-SLI Deluxe.

The specs
As usual, we'll get the ball rolling with a glance at the A8N32-SLI's spec sheet.

CPU supportSocket 939-based Athlon 64 and Sempron processors
North bridgeNVIDIA nForce SPP 100
South bridgeNVIDIA nForce4 SLI
InterconnectHyperTransport (8GB/sec)
Expansion slots2 PCI Express x16
1 PCI Express x4
3 32-bit/33MHz
Memory4 184-pin DIMM sockets
Maximum of 4GB of DDR266/333/400 SDRAM
Storage I/OFloppy disk
2 channels ATA/133 with RAID 0, 1, 0+1, and 5 support
4 channels Serial ATA with
RAID 0, 1, 0+1, and 5 support
2 channels Serial ATA with RAID 0, 1 support via Silicon Image 3132
Audio8-channel AC'97 audio via nForce4 SLI and Realtek ALC850 codec
Ports1 PS/2 keyboard
1 PS/2 mouse
1 Parallel port

4 USB 2.0 with headers for 6 more
1 RJ45 10/100/1000 via Marvell 88E8053
1 RJ45 10/100/1000 via nForce4 SLI

1 analog front out
1 analog bass/center out
1 analog surround out
1 analog rear out
1 analog line in
analog mic in
1 Coaxial digital S/PDIF output
1 TOS-Link digital S/PDIF output

Headers for 2 Firewire ports via Texas Instruments TSB43AB22A
Header for 1 game and 1 serial port
BIOSPhoenix AwardBIOS
Bus speedsHT: 200-400MHz in 1MHz increments
DRAM: 100, 133, 166, 183, 200, 216, 233, 250MHz
PCI-E: 100-200MHz in 1MHz increments
LDT: 1000, 800, 600, 400, 200MHz
SB-to-NB: 200-300MHz in 1MHz increments
VoltagesCPU: auto, 1.0-1.5625V in 0.0025V increments
DDR: auto, 2.50-4.00V in 0.05V increments
HT: 1.2-1.3V in 0.1V increments
NB: default, 1.3V
: default, 1.6V
MonitoringVoltage, fan status, and temperature monitoring
Fan speed controlCPU, Chassis, Power

NVIDIA's older nForce4 chipsets are single-chip designs, but the nForce4 SLI X16 has traditional north and south bridge chips. The north bridge serves up 18 lanes of PCI Express, 16 of which are dedicated to the board's first x16 graphics slot. Secondary graphics cards hang off the south bridge, which provides 16 lanes of PCI-E connectivity for graphics and an additional four lanes for additional PCI-E slots and peripherals. With secondary graphics cards hanging off the south bridge, the nForce4 SLI X16's chip-to-chip interconnect is particularly important. NVIDIA uses a 16-bit, 1GHz HyperTransport link to connect the chipset's north and south bridge components, yielding as much bandwidth (8GB/s) between the north and south bridge chips as the chipset has between itself and the Athlon 64 processor.

As it turns out, the speed of the nForce4 SLI X16's link to the CPU may help us predict whether the chipset's additional PCI Express lanes will help SLI performance. Increasing the number of PCI Express lanes allocated to each graphics card from eight to 16 boosts available graphics bandwidth from 2GB/s to 4GB/s in each direction, going to and from the graphics card. However, the nForce4 SLI X16's HyperTransport processor link only offers 4GB/s of bandwidth in each direction, so it can only fully saturate one 16-lane graphics slot at a time.

Of course, secondary graphics cards will also have to compete for interconnect bandwidth with the nForce4 SLI X16 south bridge's other features, including its ActiveArmor-accelerated Gigabit Ethernet and RAID. NVIDIA's RAID controller is perhaps the more impressive of these two features, as it's capable of spanning multiple arrays across both ATA and Serial ATA drives. Support for RAID 5 arrays has also been added to the storage controller's arsenal, a feature that has previously only been available on the company's Intel Edition chipsets. As one might expect, the nForce4 SLI X16 chipset retains support for 300MB/s Serial ATA transfer rates, as well.

Asus also equips the board with secondary GigE and SATA RAID controllers. The auxiliary Gigabit Ethernet option may come in handy for those leery of NVIDIA's GigE implementation, and the extra SATA ports can be useful for reasons we'll elaborate on in a moment. Both chips use PCI Express, leaving a Texas Instruments Firewire chip as the only device on the motherboard's PCI bus.

While the nForce4 SLI X16 chipset represents a refinement of previous nForce4 designs, it doesn't address the chipset's greatest weakness: its basic AC'97 audio controller. Not that we expect the world, but new high-end chipsets should at least support high-definition audio. Instead, the A8N32-SLI is stuck with AC'97 and a Realtek ALC850 codec. Hail to the crab, baby.