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NVIDIA's nForce3 250Gb chipset

Upping the ante for Athlon 64

ALTHOUGH NVIDIA'S nForce2 chipset was a darling of the enthusiast and gaming community, the company's nForce3 150 didn't fare so well. The nForce3 150 was available as early as the Opteron launch, but the chipset's comparably weak feature set and initially uninspired performance drove many to VIA's faster and more feature-rich K8T800 chipset.

The K8T800 has enjoyed the lead in both features and performance since its introduction, but the tables may turn with the release of NVIDIA's nForce3 250Gb chipset. The 250Gb beefs up the nForce3's HyperTransport link and adds Gigabit Ethernet, Serial ATA and IDE RAID, a working AGP/PCI lock, and a hardware-accelerated firewall to the chipset's arsenal of integrated features.

Can the nForce3 250Gb's updated feature set and performance help NVIDIA capture the Athlon 64 chipset crown? Read on to find out.

More on-chip features for the 250Gb
The nForce3 250Gb retains the same single-chip design as its predecessor, the nForce3 150, but beyond that, there are few similarities between the two chips. Apart from sharing an AGP 8X interface, two ATA/133 ports, and AC'97 audio with the nForce3 150, the 250Gb is all new. Some of the chipset's more notable new features are:

  • Serial ATA — Serial ATA support didn't make it into the nForce3 150, but NVIDIA redeems itself by supporting a total of four SATA devices on the 250Gb. The chipset has internal ports for two Serial ATA devices, and another two ports can be served through an external PHY chip.

  • Robust RAID — The nForce3 250Gb supports RAID 0, 1, 0+1, and JBOD arrays across all four of its Serial ATA ports, but that's not all. RAID arrays can also be configured using drives connected to the 250Gb's two ATA/133 IDE channels, and the chipset even supports RAID arrays that span both Serial ATA and ATA/133 drives. The 250Gb's support for ATA/133 RAID is particularly notable because the VIA VT8237 south bridge only supports RAID for Serial ATA drives.

    In addition to supporting multiple RAID arrays on or across multiple storage channels, the nForce3 250Gb can be configured with spare disks and even hot standby drives for mission critical arrays. The 250Gb also supports on-the-fly rebuilds for mirrored arrays.

  • Gigabit Ethernet — The price of Gigabit networking hardware is falling at a remarkable rate, making 1000Mbps networks an affordable reality for businesses and even bandwidth-hungry enthusiasts. Gigabit Ethernet is nothing new in the motherboard world, where GigE chips have been riding the PCI bus and Intel's CSA north bridge link for some time. However, the nForce3 250GB's Gigabit MAC resides directly on the chip where it has unfettered access to the chipset's HyperTransport bus.

    Although the nForce3 250Gb's Gigabit MAC is integrated into the chipset, it uses a PHY chip to act as an Ethernet transceiver. The 250Gb's GigE implementation supports TCP and checksum offloads to reduce CPU utilization, plus jumbo frames to improve throughput by reducing frame overhead.

  • A hardware-accelerated firewall — I'll look at the nForce3 250Gb's firewall in more detail in a moment. However, it's worth noting here that the firewall in the only native, hardware-accelerated one of its kind. Acceleration should help reduce the firewall's CPU utilization, and NVIDIA is even letting third-party software developers take advantage of the nForce3 250Gb's dedicated firewall hardware.

    The firewall's hardware components have benefits beyond lower CPU utilization, though. Because it partially resides in hardware, the firewall is enabled instantly when a machine is powered on. Software firewalls that rely on drivers and other programs can only protect a machine after it boots into the OS and all the necessary drivers and programs are loaded, leaving a small window for attacks to take hold.

  • A wider, faster HyperTransport link — NVIDIA caught some flak for the nForce3 150's relatively pokey 16-bit/600MHz downstream and 8-bit/600MHz upstream HyperTransport connections, but the nForce3 250Gb's HT links are 16-bit and 800MHz in both directions. The nForce3's faster HT connection nicely matches the K8T800's 16-bit/800MHz HyperTransport link, but this isn't just a case of keeping up with the Jonses; the 250Gb's integrated Gigabit Ethernet and Serial ATA RAID need more bandwidth than a slower HT link can provide.

  • A working AGP/PCI lock — The nForce3 150 was supposed to have a working AGP/PCI lock, but retail boards never quite got it right. NVIDIA is adamant that the nForce3 250Gb's AGP and PCI locks work, which should be music to the ears of overclockers looking to crank up the CPU clock without running graphics cards or other system components out of spec. However, it will ultimately be up to motherboard manufacturers to support bus locking and overclocking.

  • Two more USB ports — Though it's only a minor upgrade, it's worth mentioning that the nForce3 250Gb supports eight USB 2.0 ports—two more than the nForce3 150.

The SoundStorm APU's hardware acceleration and Dolby Digital encoding capabilities are sorely absent from the nForce3 250Gb, but at least the chipset's strong Serial ATA, RAID, and GigE implementations soften the blow. The plentiful on-chip peripherals also make the 250Gb's lack of PCI Express support easier to swallow. I suspect that few users will encounter PCI bandwidth sharing problems with the nForce3 250Gb.