Author Topic: First PCI Express Graphics Cards Arrive (Aug 2004)  (Read 2307 times)

Offline chrisNova777

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First PCI Express Graphics Cards Arrive (Aug 2004)
« on: March 06, 2018, 11:38:48 AM »

Lovers of high-end PC graphics rejoiced at news of the recent launch of desktops with PCI Express-based chip sets that promise dramatically faster graphics throughput than today's AGP 8X standard. But a preliminary look at two of the first PCI Express cards suggests that the spec will have more impact on future graphics headroom than on immediate performance gains.
In fact, our tests showed practically no performance difference between graphics cards using the AGP 8X interface and those using PCI Express. Though PCI Express 16X supports concurrent transfers of up to 4 gigabytes per second compared with AGP 8X's 2.1 GBps of shared bandwidth, even today's most graphics-intensive PC games have yet to turn the AGP conduit into a bottleneck.

We tested boards based on graphics chips from NVidia and from ATI. NVidia sent us an early PCI Express reference board using its GeForce 6800 GT chip and 256MB of memory; ATI provided a preproduction version of its board using the Radeon X600 XT chip and 128MB of memory. Retail cards based on the NVidia GeForce 6800 GT chip should be shipping by the time you read this and will sell for about $399. Cards based on ATI's Radeon X600 XT chip should be on shelves, too, selling for about $199.

We used two AGP comparison boards. One was Leadtek's $400 shipping WinFast A400 GT board with the NVidia GeForce 6800 GT chip (the same chip that the NVidia PCI Express board uses) and 128MB of memory. The other was VisionTek's $200 shipping Xtasy 9600 XT, which is based on ATI's Radeon 9600 XT chip (a chip different from but comparable to the ATI PCI Express board's X600 XT) and has 256MB of memory. Ideally, each of our test cards would have included the same memory allotment, but supply constraints left us with mismatched amounts of memory.

Comparing the AGP graphics cards with their newer PCI Express cousins proved dicey because there's no way to test both kinds of boards in the same PC (though at least one chip set vendor is contemplating producing a dual AGP/PCI Express product). Instead, the PC World Test Center matched comparably configured systems from the same vendor: one using Intel's PCI Express-based 915G chip set, and another using Intel's 865G chip set with 8X AGP.

Since the ATI and NVidia chips are geared toward different buyers (the NVidia GeForce 6800 GT is a higher-end chip), we compared only ATI with ATI and NVidia with NVidia. The two companies also differ in their method of implementing PCI Express. ATI chose a "native" implementation tailored to PCI Express from the ground up, while NVidia's early products (including the 6800 GT) use a bridge technology between the PCI Express interface and the company's existing AGP-based chips. Each company claims its approach makes more sense; our tests--using preproduction drivers--do not permit us to resolve that matter conclusively.

Test Results
In most of our tests, the PCI Express boards finished in a virtual tie with the AGP boards. For example, in our Halo test, conducted at a resolution of 1024 by 768, the ATI-based VisionTek AGP card reached 34 frames per second while ATI's PCI Express card notched 35 fps. The two NVidia-based cards were separated by just 1 fps (59 versus 58) as well. The same test run at 1600 by 1200 resolution netted precisely matched results from both cards. (For complete test results and information on how we test, see the chart below.)

The only significantly different results we saw came in our tests of the ATI cards using Splinter Cell: The AGP card notched 36 fps versus 41 fps for the PCI Express version at 1024 by 768 resolution; the same AGP card reached 23 fps and the PCI Express card hit 27 fps at 1600 by 1200 resolution. The higher-end NVidia produced generally higher frame rates throughout, with scores of 74 and 75 fps for the AGP and PCI Express versions, respectively, at 1024 by 768; it scored 9 fps lower on each at 1600 by 1200.

The AGP cards had a negligible advantage over their PCI Express counterparts in our Unreal Tournament 2004 test at the lower resolution. At the higher resolution, scores for the NVidia cards stayed exactly the same; but ATI's PCI Express card slowed dramatically to just 34 fps versus 46 fps for the AGP card. This result may be due to differences in memory capacity and chip sets, or to driver issues.

Skip PCI Express?
Our test results do not mean that you should plan to pass over PCI Express-based desktops and graphics cards, but there's clearly no need to rush out and buy a new PCI Express-based PC just for the graphics. Going forward, many systems will integrate PCI Express by default, which means you won't pay anything extra to get it. And once software begins to use the extra bandwidth, you'll likely be glad you have it.

In the meantime, making a choice between NVidia and ATI products--whether based on AGP or PCI Express--has become largely a matter of taste, as noted in our August review of AGP boards. If you're already on the PCI Express bandwagon, you won't be disappointed by either company's newest offerings.

PCI Express, AGP Boards Run Neck and Neck
Comparable graphics cards based on the next-generation interface offer about the same performance as similar AGP products in our PC games-based benchmarks.