PCI Express 2.0
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Ispada da je razlika generalno 10% i to u višim rezama.
The RV670 offers sterling support for PCI Express 2.0. The second version of PCI Express doubles the standard bandwidth, from 2.5 Gbit/s to 5 Gbit/s. As a result, the standard graphics slot (x16) can transfer data at up to 8 GB/s in each direction (marketing specialists love to sum up these numbers and specify 16 GB/s) versus 4 GB/s for Version 1.x. Besides, PCI Express 2.0 is compatible with PCI Express 1.1. Old graphics cards will work in new motherboards, and new graphics cards supporting the second version will still work in motherboards without this support. External power supply being sufficient, of course. And they won't have the increased interface bandwidth.
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It's not easy to evaluate the real effect of higher PCI Express bandwidth on performance - tests should be run in equal conditions, which is problematic. But higher bandwidth won't hurt, especially for SLI/CrossFire systems that exchange data via PCI Express as well. Besides, lots of modern games require large volumes of fast memory. When there is not enough video memory, a game will use system memory, so PCI Express 2.0 will certainly be welcome.
AMD publishes the following data for RADEON HD 3850 with 256 MB of memory: performance difference between systems with PCI Express 1.x and 2.0 in Company of Heroes, Call of Juarez, Lost Planet, and World In Conflict varies from 5% to 25%, about 10% on the average. In high resolutions of course, when a frame buffer and contiguous buffers occupy the biggest part of local video memory, and some resources are stored in system memory.
To provide backward compatibility with existing PCI Express 1.0 and 1.1 solutions, Specifications 2.0 support both 2.5 Gbit/s and 5 Gbit/s transfer rates. Backward compatibility of PCI Express 2.0 allows to install older 2.5 Gbit/s solutions in 5.0 Gbit/s slots, which will operate at a lower speed. And devices designed in compliance with Specs 2.0 will support both 2.5 Gbit/s and 5 Gbit/s. As usual, it's all good on paper, but engineers may encounter some compatibility problems with some combinations of motherboards and expansion cards.
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