PCI Express 2.0 backwards compatible?

[Danior]

hi,
I have a question PCI Express 2.0 is backwards compatible to PCI Express 1.0/1.1? .My motherboard which I got a few days ago has the older 1.0a spec. My motherboard is a Biostar P4M900-M4 ver.6.x with latest Bios.Any help will be extremely appreciated.

[kiLLer]

hi,
All of the new graphics cards that support PCIe 2.0 are backward compatible with motherboards that support only PCIe 1.1. BOTH Pcie 2.0 and 1.1 standards USE the x16 PCIe slot.

Actually the new cards would hardly be slowed down by the PCIe 1.1 slot. PCIe 2.0 has a wide bandwidth that could hardly be utilized by most single cards. It is the dual or quad GPU set up that would benefit most from PCIe 2.0.

[ApPy10]

Hi,
yes it is already backwards compatible, I myself also have a HD4830 PCIe 16x on Ver. 1.0 run. Why do you want to know?

[Birdie]

PCI Express (Peripheral Component Interconnect Express), officially abbreviated as PCIe, is a computer expansion card standard designed to replace the older PCI, PCI-X, and AGP standards. PCIe (or PCI-E, as it is commonly called) is the latest standard for expansion cards that is available on mainstream personal computers.
a PCIe card will physically fit (and work correctly) in any slot that is at least as large as it is (e.g. an x1 sized card will work in any sized slot);
a slot of a large physical size (e.g. x16) can be wired electrically with fewer lanes (e.g. x1, x4, or x8) as long as it provides the power and ground connections required by the larger physical slot size.

[Majestic_Lizard]

Some people seem to be overlooking that the poster is referring to PCI-Express 1.0a and NOT 1.1. There is a BIG difference. A newer card designed for PCI-Express 2.0 will work in a PCI-Express 1.1 slot with little discernible performance decrease.

However, a newer card designed for PCI Express 2.0 will work in a PCI-Express 1.0a slot with very obvious performance decrease and stability problems and in some instances, depending on the chipset, the system will eventually not even recognize the card. 1.0a PCI-E boards were before the standards for PCI-E were adequately normalized and thus the performance varies greatly from board to board as a consequence of differences in voltage through the bus.

I've run PCI-E 2.0 cards on systems that were essentially identical in all respects except for the revision of the PCI-Express interface. In a PCI-express 1.1 system that had an Intel Dual Core with 2 GB of RAM and a 500 Watt power supply, a 9600 GT ran Crysis on 1280x1024 and high settings at about 25 FPS average. On system that was virtually identical but had the 1.0a PCI-E, the same card ran at about 8 to 11 FPS on exactly the same settings. On another 1.0a PCI-E system that actually had a faster processor, the 9600 GT was not even recognized at all.

Meanwhile, older cards like the 7800 GTX and the x1950 pro had exactly the same performance on all three systems. So basically, if you have the PCI-express 1.0a, stick with an older card.