I just bought an LSI SAS 9211-8i HBA(Host bus adapter) to use with my new hardware. I realized after looking at the card that it required an x8 slot and my new mobo only x16 available. I keep on reading that PCI-E specs are backwards compatable however when I try to install Windows 7 on it it does not find the RAID Controller and now I am really confused. Can anyone help with this one?


Yes, in the general case you can install PCI-E cards in any PCI-E slot that will physically accept the card. If there are fewer PCI-E lanes available than the card requires, it should run a little slower but still run. If there are more lanes, it will just use what it needs.

PCI-E 1 and PCI-E 2 should not be a problem either.

Regarding Windows 7 not finding the RAID controller, I do of course assume that you're using the proper driver for the RAID card? And that if you're installing the OS onto a RAID volume, that you're loading the drivers during installation...

If all this is the case, then my guess is that you're using a consumer class desktop motherboard. Some desktop boards have PCI-E x16 slot which will only work with graphics cards. This goes against the intentions of PCI-E, but some manufacturers don't bother to do anything about this, since desktop machines almost always use the fastest PCI-E slots for graphics. Try contacting your motherboard maker / PC suppliers support..

  • Thanks for the reply. By the way this is the motherboard that I am using: newegg.com/Product/Product.aspx?Item=N82E16813131365 It is an ASUS P6T Deluxe V2 LGA 1366 Intel X58 ATX. No where does it state that the PCIe x16 slots only work with Graphics cards and I checked a couple of times and the RAID Controller that I got actually states that Windows 7 supports it out of the box with no drivers needed. I have even attempted at installing a RAID Driver for it but the installer does not recognize it. I RMAed my mobo and I hope I don't have to get the RAID RMAed also. – iLya Lozovyy Oct 20 '09 at 12:06
  • Try writing to Asus's tech support, and ask if the mobo supports a non-graphics card in its x16 slot. Of course I don't know that specific motherboard, but it sounds like a likely cause of the problem. Could also be that the RAID controller is dead of course, which you can check if you have another machine to test it in. – Jesper M Oct 20 '09 at 12:31

Yes, you can plug x8 cards into x16 slots. It's more likely that your problem is that you've got a PCIe Gen2 (version 2.0) card in a motherboard which doesn't know how to deal with that. Try a BIOS upgrade.

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