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Intel's G45 Express chipset


Blu-ray decode acceleration comes to the Graphics Media Accelerator
— 10:37 PM on October 9, 2008

There was a time when enthusiasts had little interest in integrated graphics chipsets. At best, we only considered the IGPs of yesteryear as platforms for the next PC we'd build our mothers or corporate desktops we'd deploy to the masses of slack-jawed users in our domains. Older integrated graphics solutions simply didn't have the graphics horsepower to run games—not just at acceptable frame rates, but at all—and they didn't offer much in the way of video playback acceleration.

Lately, however, integrated graphics chipsets have enjoyed a renaissance. AMD and Nvidia are using functional blocks ripped from their high-end GPU architectures, assuring not only broad compatibility with games, but surprisingly adequate performance. These graphic cores have also been bestowed with dedicated video processing engines that serve up silky Blu-ray playback with even an Econobox sub-$100 CPU. And the chipsets as a whole have become quite energy-efficient, too, capturing the attention of enthusiasts looking to build silent PCs for their living rooms.

AMD and Nvidia have moved the goal posts forward by quite a leap with their latest integrated graphics chipsets, but what about Intel? The chip giant is the overwhelming integrated graphics sales leader, commanding the lion's share of the overall graphics market on the strength of its IGP business alone. What does Intel's latest G45 Express integrated graphics platform bring to the table?

  • DirectX 10-class unified shader architecture? Check.
  • Full Blu-ray decode acceleration? Check.
  • Second-generation PCI Express slot for discrete graphics upgrades? Check.
  • Proven south bridge with all the feature boxes, er, checked? Check.
  • Front-side bus that hooks into the spoils of Intel's Core 2 processor lineup? Bonus!

On paper, the G45 Express certainly looks like it should be able to run with the new IGP order. But can Intel really compete with the graphics specialists on their home turf? There's only one way to find out. Please, contain your excitement.


The G45 exposed
Integrating graphics functionality is the G45 Express' raison d'être, so that's the best place to start. The chipset's north bridge component houses its graphics core: the Graphics Media Accelerator X4500HD. This GPU is an extension of the GMA X3500 architecture found in Intel's older G35 Express chipset, bringing the X4500HD DirectX 10-class unified shaders with support for Shader Model 4.0 and OpenGL 2.0. While the individual shaders cores haven't changed much for the X4500HD, there are two more of them, for a grand total of 10. These cores are running faster, too, with Intel cranking their clock speed from 667MHz in the X3500 to 800MHz in the X4500HD.

As far as the 3D pipeline is concerned, the X4500HD is a mildly hopped-up X3500. Intel has added a couple of cylinders and slapped on a turbo, but we're still dealing with the same tired car analogy. The X3500's gaming performance failed to impress, which doesn't leave much room for optimism that the X4500HD will be a big improvement. We'll find out for sure in a moment.

Fortunately, there's more to the G45 Express' graphics core than added horsepower. The X4500's HD moniker actually means something, denoting support for Blu-ray decode acceleration. Intel makes use of both fixed-function logic and the X4500's shader processors here, assisting with nearly every step in the decode process for the MPEG2, VC-1, and AVC/H.264 video formats.

Like AMD and Nvidia, Intel also has its own collection of de-interlacing and post-processing schemes to enhance HD video quality. We're not entirely sure how useful those features will be given the quality of commercial Blu-ray releases, though.

Those same commercial Blu-ray titles tend to be encrusted with a thick layer of DRM, so it's no surprise that the X4500HD offers support for both HDCP and the Protected Audio/Video Path. These necessary evils are essential to protect end users from the dangers of fair use, or something.


One of the more impressive elements of the G45's graphics component is its robust output capabilities. The chip can simultaneously drive up to two digital displays via DVI, HDMI, and DisplayPort outputs. You can feed multi-channel LPCM audio over HDMI, too—something even AMD's beloved 780G can't hack.

Like most integrated graphics implementations, the X4500HD carves itself a slice of system memory, in this case via the G45 Express's dual-channel memory controller. This memory controller supports DDR2 up to an effective 800MHz and DDR3 up to 1066MHz, offering a healthy amount of memory bandwidth to the graphics core. And with support for front-side bus speeds up to 1333MHz (333MHz quad-pumped), the G45 has plenty of system bandwidth to go around, too.

Speaking of bandwidth, you'll find 16 lanes of second-generation PCI Express in the G45's north bridge component. That's enough lanes to provide a single graphics card with 8 GB/s of bi-directional bandwidth, should you wish to forgo integrated graphics in favor of a discrete GPU. The lanes are consolidated in a single link and can't be split into a pair of x8s without additional hardware, making it unlikely that we'll see a G45-based answer to AMD's mutant 790GX integrated graphics/Crossfire platform.

With all the G45's PCI Express lanes tied up in an x16 slot, we have to look to the south bridge for additional lanes for x1 slots and peripherals. The G45 is designed to work with Intel's ICH10 south bridge family, whose members offer six PCIe lanes of their own. These lanes are only gen-one, but they still offer plenty of bandwidth for the sorts of peripherals one might pair with a budget desktop system or home theater PC.

AMD 780G Intel G45 Express Nvidia GeForce 8300
Processor interface 16-bit/2GHz HyperTransport 800/1066/1600MHz front-side bus 16-bit/2GHz HyperTransport
PCI Express 1.1 lanes 0 6 0
PCI Express 2.0 lanes 26* 16 19
Multi-GPU support CrossFire NA SLI
Chipset interconnect PCIe 1.1 x4 DMI NA
Interconnect bandwidth 2GB/s 2GB/s NA
Serial ATA ports 6 6 6
AHCI Y Y Y
Native Command Queuing Y Y Y
RAID 0/1 Y Y* Y
RAID 0+1/10 Y Y* Y
RAID 5 N Y* Y
ATA channels 2 0 1
Max audio channels 8 8 8
Audio standard AC'97/HDA HDA HDA
Ethernet N 10/100/1000 10/100/1000
USB ports 12 12 12

The ICH10 south bridge family certainly doesn't want for storage options, with six 300MB/s Serial ATA ports and support for both AHCI and eSATA across the board. The vanilla ICH10 is the most likely sidekick for the G45. However, mobo makers can also opt for the ICH10R, which brings all sorts of RAID goodness to the table. Like the ICH9 series that preceded it, the ICH10 family lacks an IDE channel, forcing motherboard makers to employ third-party silicon to provide compatibility with older IDE devices. Since SATA optical drives are easy enough to find these days, though, we're not inclined to complain.

What the ICH10 family lacks in IDE support it makes up for with an integrated Gigabit Ethernet MAC. We haven't seen many mobo makers take advantage of this capability in their P45-based offerings, with most opting for GigE chips from Marvell and Realtek. That's a shame, since we've actually found that Intel's solution delivers competitive throughput with excellent CPU utilization.

A dozen USB ports rounds out the ICH10 series in unspectacular fashion. This south bridge line is really just a die shrink of the ICH9 family down to 65nm fabrication technology. The same process is used to craft the G45's north bridge chip, which should make for an energy-efficient package overall.