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Dual-core-capable Pentium platforms compared

Seven paths to single-socket SMP bliss

THE AVAILABILITY OF INEXPENSIVE dual-core Pentium D processors has some enthusiasts seriously reconsidering the Intel platform, and for good reason. SMP's creamy smoothness is hard to resist, and once you're hooked, there's no going back. AMD may have a better dual-core design and superior performance in many applications, but even the least expensive Athlon 64 X2 costs 50% more than a Pentium D 820. Heck, even the Pentium D 830 is cheaper than the X2 3800+. Oh, how times have changed.

Intel's dual-core chips may be cheap, but they won't plug into just any LGA775 motherboard. The processors require a chipset from Intel's 955/945 family or NVIDIA's nForce4 SLI Intel Edition, so upgrading is more involved than simply buying a new CPU. Fortunately, motherboard manufacturers have flocked to Intel and NVIDIA's new chipsets, so there's no shortage of dual-core-compatible motherboards from which to choose.

To help prospective Pentium D purchasers get a handle on the platforms available to them, we've rounded up half a dozen motherboards and a small form factor system that support Intel's dual-core chips. Several chipsets are represented among the competitors, and we also have entries from a number of different manufacturers, including Abit, Asus, Gigabyte, and Shuttle. Read on for an in-depth comparison of these dual-core-capable platforms.

The chipsets
Today's motherboards increasingly rely on core logic chipsets to define their features and performance, so it seems appropriate to kick things off with a quick look at the chipsets involved in today's round-up. Examining these chipsets will highlight many of the key similarities and differences between the capabilities of each motherboard.

Chipsets are traditionally made up of north bridge and south bridge chips, which we'll deal with one at a time. Let's start at the top with a comparison of the north bridges from Intel and NVIDIA.

Intel 955X Intel 945P/G NVIDIA nForce4 SLI SPP
Front-side bus 800, 1066MHz 800, 1066MHz 800, 1066MHz
Memory type Dual-channel DDR2 Dual-channel DDR2 Dual-channel DDR2
PCI Express lanes 16 16 19
North/south ridge interconnect type DMI DMI HyperTransport
Peak theoretical interconnect bandwidth 2GB/sec 2GB/sec 1.6GB/sec

Even though the only processors to require a 1066MHz front-side bus are currently $1000 Extreme Edition chips, all of these north bridge chips support the faster system bus. Enthusiasts should be astute enough to avoid paying extra for the Extreme Edition chips, but native chipset support for a 1066MHz may come in handy for those looking to overclock more affordable processors. Unfortunately, the nForce4 SLI Intel Edition doesn't work properly with Intel's most affordable dual-core processor, the Pentium D 820. The Pentium D 820 will run in nForce4 SLI Intel Edition boards, but only in single-core mode, which is a waste.

All three north bridge chips have a dual-channel DDR2 memory controller. Not all memory controllers are created equal, though. NVIDIA and Intel's memory controllers are obviously not the same, but the memory controllers within Intel's own lineup also differ. Notably, the 955X memory controller supports what Intel calls Memory Pipeline Technology (MPT), while the 945 family does not. According to Intel, MPT enables a "higher utilization of each memory channel," which should translate to greater memory bandwidth.

PCI Express is the next feature to be shared by all three north bridge chips, and while NVIDIA consolidates all 19 of the nForce4 SLI's lanes in the north bridge, Intel's north bridge chips have only 16 lanes of PCI Express. Intel prefers to offer some of its PCI-E lanes at the south bridge, which may explain why the Intel chipsets have a faster north/south bridge interconnect than the nForce4 SLI Intel Edition. A single PCI-E lane can consume up to 250MB/sec of bandwidth in each direction, and with multiple lanes, that adds up.

While we're looking at PCI Express, we should note that the nForce4 SLI chipset is capable of splitting 16 PCI Express lanes evenly between a pair of x16 slots, giving each slot eight lanes of bandwidth to play with. This is NVIDIA's recommended PCI-E configuration for SLI, and one that Intel's chipsets can't match. Some 955X-based motherboards do have a second PCI-E x16 slot hanging off the south bridge, but it generally only has access to two or four PCI Express lanes. Thus far, NVIDIA's graphics drivers don't support SLI in that configuration, although there's word that ATI's CrossFire multi-card technology will be more accommodating.

SLI is decidedly a high-end graphics solution, but for budget types, Intel's 945G chipset has a GMA 950 integrated graphics processor (IGP). IGPs generally don't offer much in the way of 3D graphics and gaming performance, and as we'll see, the GMA 950 is no exception.

PCI Express lanes 0 6
SATA ports 4 4
SATA peak data rate 300MB/sec 300MB/sec
Native Command Queuing Yes Yes
SATA RAID 0/1 Yes Yes
SATA RAID 0+1 Yes Yes
Matrix RAID No Yes
ATA channels 2 1
ATA RAID support Yes No
Max audio channels 8 8
Audio standard AC'97 HD/AC'97
Ethernet 10/100/1000 None
USB ports 10 8

As we turn our attention to the south bridge, we see even more similarities between the Intel and NVIDIA chips. There are a number of key differences to note, though. First, of course, is the Intel ICH7R's six PCI Express lanes. The Intel chips also support Matrix RAID, which can combine RAID 0 and 1 arrays using only two drives. Matrix RAID's performance is pretty impressive, and it may be the ICH7R's most appealing feature.

Unfortunately, though, the Intel south bridge's ATA support is comparably weak. The ICH7R has only a single ATA channel, but NVIDIA's nForce4 SLI MCP has two channels and support for ATA RAID. In fact, NVIDIA's nvRAID software is capable of spanning arrays across both ATA and Serial ATA drives.

The nForce4 SLI MCP also beats Intel in the networking department, where NVIDIA's hardware-accelerated Gigabit Ethernet controller and Firewall are unchallenged by the ICH7R's lack of integrated networking. Intel seems content to let motherboard manufacturers use standalone Gigabit Ethernet controllers, and many of the boards we'll be looking at today actually sport Intel GigE network controller chips.

Intel leads on the audio front, though. The ICH7R's support for high-definition sampling rates makes the nForce4's basic AC'97 audio look pretty weak, although neither south bridge's audio implementation supports hardware acceleration for 3D audio. These days, you need a separate sound card for that.