Intel's New Integrated Graphics

Intel’s New Integrated Graphics

Jason Cross

The mere mention of integrated graphics is usually enough to send any PC game player into a fit. No matter whose integrated graphics solution you look at, the prognosis is not good: they’re not nearly fast enough and don’t have many of the important new features found in even the most inexpensive add-in cards. If all you plan to do is surf the Web, write e-mail, and maybe a do little word processing or spreadsheet work, the integrated solutions are fine. Just don’t try to play a 3D game with them.

That’s been the conventional wisdom for some time now–we took a look at the three most prominent desktop integrated graphics solutions on the market a few months ago and came to the same conclusion. Even the most impressive solution at the time, ATI’s Radeon 9100 IGP, only managed to keep up with the most inexpensive add-in cards in a few games. What’s more telling is the horrible performance of the previous Intel integrated graphics technology, Extreme Graphics 2, present in the 865G chipset. It was consistently slower than the competition and less feature-rich to boot.

With the new 915G chipset, Intel aims to change all that. Along with a host of other technologies we previously covered, the new chipset includes a brand-new graphics architecture. Gone is the “Extreme Graphics” moniker – this new graphics core is called the Graphics Media Accelerator 900 (GMA 900). This new architecture aims to provide much greater speed and more relevant modern features, including Pixel Shader 2.0 support. Today, we run it through the gauntlet and see if it’s good enough to make those cheap add-in cards obsolete.

At the most basic level, the improvements in the GMA 900 can be boiled down to three categories: faster clock speed, more pipes, and pixel shader 2.0 support. The Extreme Graphics 2 core in the 865G chipset ran at 266MHz and had two rendering pipelines. With the GMA 900 the clock speed has been increased to 333MHz and the pipelines doubled to four. This more than doubles the total potential pixel fill rate from 533 million pixels per second to about 1.3 gigapixels per second.

As with Extreme Graphics 2, but unlike integrated graphics from Nvidia or ATI, the GMA 900 includes no geometry processing capabilities – neither a fixed-function T&L processor nor hardware vertex shader unit. Rather, it relies on the CPU to process all geometry functions. From there, the GMA 900 in the 915G chipset handles vertex setup, texture application and pixel shading, and rasterization.

To conserve memory bandwidth, Intel uses a slightly updated version of the zone rendering technology they used in Extreme Graphics 2. This “Zone Rendering 3” technology breaks the scene up into small rectangular block and renders one entire block before moving on to the next. While rendering, the technology employs tricks like early checks of the Z value to avoid drawing pixels you won’t see. Intel explains some of the benefits of Zone Rendering 3 this way:

Like conventional rendering, the scene is passed to the geometry processing engine where the polygons are transformed into view space. However, instead of then going directly through screen space conversion, Intel GMA 900 first sorts each polygon into memory, based on their location on the screen (zone). Since each zone can be processed entirely on-chip, the depth-testing and pixel blending operations are completed and the fully rendered zone is written out to the frame buffer – requiring each pixel to be written to memory only once.

The whole point of this is to save memory bandwidth, which is critically important when the graphics chip is sharing memory with the CPU. Stand-alone graphics cards and other integrated graphics technologies employ similar bandwidth-saving schemes. In fact, some modern cards also employ lossless color compression, which the GMA 900 does not. Bandwidth savings aside, the GMA 900 will simply have more memory bandwidth available to it. Since the chipset supports DDR2 memory at speeds up to 533MHz, the 6.4GB per second available to previous integrated graphics technologies has been boosted to 8.5GB/sec.

Of course, the most significant update to the graphics core is probably support for DirectX 9.0b’s pixel shader 2.0. Intel wouldn’t say whether they process floating point shaders in 24-bit or 32-bit mode, or support the 16-bit partial precision feature. Given the priority on keeping the 915G die size small, it’s reasonable to suspect that only the minimum 24-bit floating point precision is supported. Still, the combination of CPU-driven vertex shader 2.0 and GMA 900-driven pixel shader 2.0 makes this the world’s first fully DirectX 9.0b compliant integrated graphics part.

Here’s how the basic features of the modern integrated graphics cores stack up:

Feature

Radeon 9100 IGP

nForce 2 – 400

Intel Extreme Graphics 2

Intel GMA 900

RAM support

Up to dual-channel DDR400

Up to dual-channel DDR2 533

Maximum memory bandwidth

6.4GB/sec

8.5GB/sec

Hardware T&L

DX8 vertex shaders

DX7 fixed function

None

Rendering pipelines

Clock speed

300MHz

200MHz

266MHz

333MHz

Maximum Fill Rate

600 megapixels

400 megapixels

533 megapixels

1.3 gigapixels

Pixel Shader Support

Yes, up to Pixel Shader 1.4

None

Yes, up to Pixel Shader 2.0

Other Features

Compressed textures, dot3 bump mapping, cube environment mapping

Compressed textures, volumetric textures, shadow maps, two-sided stencil

Not all the improvements in the GMA 900 are on the 3D graphics side, though. The bob-and-weave deinterlacing for video has been improved, with the aim of better supporting hi-definition video on the PC. This dovetails nicely with the improved audio support in the new Intel HD Audio. The new integrated DAC runs at 400MHz, supporting resolutions up to 2048×1536 at 85Hz. Display device support has been expanded as well–Intel now supports CRTs, LCDs, and televisions, with greatly expanded support for wide-aspect viewing modes. What’s more, dual-display configurations are now supported, with both cloning and extended desktop modes.

Of course, all the new features in the world don’t mean much if the performance is undesirable. We ran the new GMA 900 on a 915G-based motherboard through a series of tests. For comparison’s sake, we’ll include the Extreme Graphics 2 and Radeon 9100 IGP benchmarks from our integrated graphics comparison. Just to see how well the latest integrated solution stacks up against one of the cheapest add-in cards you could replace it with, we ran our tests on a new Radeon X300. This 128MB card is based on the same technology as the Radeon 9600 and should cost about $100 in the 128-bit configuration we tested. A cheaper 64-bit version will also eventually be available.

Component

Radeon 9100 IGP configuration

Intel Extreme Graphics 2 configuration

Intel GMA 900 configuration

Radeon X300 configuration

CPU

3.0GHz Pentium 4 (800MHz FSB)

3.4GHz Pentium 4 Extreme Edition

Motherboard and Chipset

Shuttle XPC SFF PC, ATI RS300 chipset

AOpen XCcube SFF PC, Intel 865G chipset

Intel 915GUX

Intel 915G

Memory

2 x 512MB (1GB) Kingston DDR400, CAS 2.5-3-3

2 x 512MB (1GB) Micron DDR2/533 Modules at CAS 3-4-4-12

Hard Drive

80GB Western Digital WD800JB

2 x WD740 10,000RPM SATA drives configured as a RAID 0 striped array, 128K block size

Optical Drive

Plextor 16/10/40A CD-RW

Toshiba DVD-ROM

Audio

Host-based, AC’97 audio

Host-based, Intel HD Audio

Operating System

Windows XP Professional, SP1 and DirectX 9.0b installed

Our test configurations are very similar, all utilizing 1GB of the fastest supported memory with a reasonable CAS latency and integrated audio, though we disabled audio in all tests to eliminate its impact on the CPU. Our hard drives and optical drives are different between our new and old tests, but those won’t affect 3D graphics performance benchmarks.

The one major difference worth noting is the CPU. Our old integrated graphics article used systems configured with a 3.0GHz “Northwood” Pentium 4 CPU. Our new 915G based system (for both integrated graphics and the X300) uses a top-of-the-line 3.4GHz Pentium 4 Extreme Edition. While this will definitely make a difference in all game benchmarks, it gives the Intel graphics solution a particular boost, since all geometry processing is handled by the CPU. As you look at our benchmarks, bear in mind the difference in CPU speed between our old and new tests.

In the case of the integrated graphics solutions, we always set the BIOS to allow the graphics core to use the maximum available amount of RAM. In the case of the Radeon 9100 IGP and GMA 900, that’s 256MB. For Extreme Graphics 2, that’s only 32MB. Both Extreme Graphics 2 and GMA 900 dynamically allocate 3D frame buffer memory as needed, though.

Integrated graphics are really not well suited to high resolutions or demanding features like anti-aliasing. We therefore ran all benchmarks at two resolutions: a low-res 640×480 test and a more demanding 1024×768 test. In all tests, sound was enabled and VSync disabled.

3DMark 2003 requires a graphics chipset capable of supporting at least DirectX 8 class pixel shaders and needs DirectX 9’s pixel shader 2.0 to complete Game Test 4, the challenging Mother Nature scene (though you can get a 3DMark score without running that one scene). Since the new GMA 900 supports pixel shader 2.0, we opted to use this newer, more relevant 3DMark instead of the old 2001 version.

Obviously we only have scores for the X300 and GMA 900 here, as they are the only graphics technologies in our sample group capable of completing all four game tests. Intel’s score isn’t awful for integrated graphics, but it is soundly beat by even a $100 PCI-Express add-in card.

The most demanding scene in the benchmark, and the only one that makes use of pixel shader 2.0, is the fourth game scene–Mother Nature. Looking just at the framerate in that test, we see our $100 PCI-E add-in card delivers three times the performance of Intel’s new integrated graphics. Note that using a lower cost card, that might only have a 64-bit wide memory interface, would result in lower scores for the add-in board — but that’s likely to still be higher than the 1570 posted by the integrated solution.

AquaMark 3 makes use of all pixel shader versions up to 2.0, but has fallback rendering paths for older hardware, which produces the same effects with multi-pass rendering techniques. The good news here is that the GMA 900 is easily twice as fast as the old Extreme Graphics 2. Granted, a part of that speed benefit may come from the faster processor in our GMA 900 test rig, but we chalk up the bulk of the improvement to extra memory bandwidth and double the pixel pipelines. Sadly, even our 3.4GHz P4-EE equipped GMA 900 test machine only barely matches the Radeon 9100 IGP, despite the fact that ATI’s integrated graphics was running on only a 3.0GHz CPU. The X300 delivers more than double the performance.

In Flight Sim 2004, we set all the graphics options to “Medium High.” Note that the 640×480 low-res benchmarks are actually 800×600 for that title – this is the lowest resolution it supports. Our new GMA 900 and X300 tests ran Halo using the more demanding pixel shader 2.0 path, but in our old tests the game was run with the -useff command line parameter to force use of the fixed-function pipeline rendering path. This was necessary, as Intel’s Extreme Graphics 2 supports no shaders at all. The “Antalus” botmatch in Unreal Tournament 2004 was run with graphics settings set to their highest.

It’s odd to see that the GMA 900 actually ran Flight Sim 2004 a couple frames per second slower than Extreme Graphics 2, even using the same settings. Other tests ran much faster, but the Serious Sam SE benchmark shows that perhaps Intel’s OpenGL driver needs some optimization. While the Halo score looks about equal, the 865G runs the game in the “way ugly” fixed-function mode that sacrifices a great many graphics effects–and it still didn’t render detail textures. To achieve the same framerate in pixel shader 2.0 mode will accurate rendering is a major improvement.

Neither of the Intel-based graphics solutions will run Comanche 4. That game looks for hardware T&L and cannot function without it.

At higher resolutions, the situation looks even better for the GMA 900, relative to the old Extreme Graphics 2. Again the Flight Sim 2004 score looks odd and the OpenGL drivers need work, but most other games run twice as fast. Unreal Tournament 2003 is actually three times as fast on the new 915G chipset. Halo has the same caveat as at 640×480 – the old Extreme Graphics 2 ran in low-quality fixed function mode and still didn’t fully display the scene correctly.

As much of an improvement as GMA 900 is over Extreme Graphics 2, the Radeon 9100 IGP still manages to run all our test games faster – and again, ATI’s integrated graphics were handicapped by a 3.0GHz Pentium 4 while the GMA 900 used a 3.4 P4 Extreme Edition. That’s not good news for Intel. Pixel Shader 2.0 support or no, the fact that ATI’s older integrated graphics (with pixel shader 1.4 support) runs everything faster with a slower CPU is not good news. We think Intel might need to bite the bullet and consider geometry processing in their next-gen integrated graphics core.

Of course, the X300 smokes everything. It’s amazing what even a $100 add-in card can do for game performance.

So much has changed with Intel’s new integrated graphics platform, and yet so much is still the same. With more than twice the pixel fill rate, more memory bandwidth, and pixel shader 2.0 support, the GMA 900 is a huge step up from Extreme Graphics 2. Microsoft’s latest guidance about Longhorn’s requirements for the fancy new “Aero Glass” interface is that it will require pixel shader 2.0 support and a fill rate of at least 1 gigapixel, which just so happens to fit within the GMA 900’s capabilities. We also found game-playing to be much more enjoyable with a 915G system than with an 865G one. A resolution of 1024×768 with detail levels maxed out is a bit much to ask, but by turning down the graphics settings a notch or two, we could comfortably and smoothly run any modern game at 800×600 and a few even at 1024×768. That’s pretty good for integrated graphics and it hits the target Intel was aiming for.

And yet, it’s not that good. The best competing integrated graphics solution, ATI’s Radeon 9100 IGP, manages to be as fast or faster, even with a slower CPU and RAM. Even inexpensive graphics cards, like our $100 X300, are several times faster than the GMA 900. If you plan on playing games with your PC, buying a modern add-in card, even an inexpensive one, is the best thing you can do to your system.

Still, in those PCs priced $500 and under, add-in cards are simply too pricey. For that market, the game-playing potential of the GMA 900 moves Intel’s platform major steps forward. Couple that with dual-display support and better support for widescreen displays and the in improvements Intel has made to its integrated graphics core are definitely laudable. We only wish they would continue to push integrated graphics forward more aggressively, rather than waiting three years for each major revision.

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