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Card works in PCI express 4x, but not in PCI express 16x

Hi all,

I haven't gotten into the computer scene for 4-5 years now...so I'm really outdated.

My question right now is, I got a old PC with Asus A8N-E motherboard. I recently brought a XFX Radeon HD 4850. Initially, everything went smoothly and I was able to boot with displays. However, afterwards it stopped displaying images. I had a 480W PSU, so I thought maybe it was too low. I swapped to a new 600W PSU and still samething.
This card was installed in the PCI-E 16x slot. Then I switched to the PCI-E 4x slot, and I was able to get display. Is something wrong with my motherboard? or is it just too old?...
I heard that PCI-E 2.0 cards can still work with PCI-E 1.0 slots. Is it safe to run my card in the PCI-E 4x slots?

Any help would be great thanks
7 answers Last reply Best Answer
More about card works express express
  1. You can run the card in an x4 slot but you will see severely reduced performance due to the much lower bandwidth of the x4 slot. If you have another PCI Express video card lying around, try connecting it to the x16 slot. If the other card works then there is something wrong with the 4850. If the alternate card doesn't work then there is a problem with the x16 slot.

    It does sound like a mobo problem if the 4850 was working in the x16 slot earlier. Did you update your video card's drivers shortly before this problem occurred? Did you do a BIOS flash shortly before this issue occurred?
  2. PCIe-x16 card should not fit into an PCIe-x4 slot. If it fits in, then it is a PCIe-x16 slot that operates at x4 speed.

    I suggest reseating the card and its power connectors because they may have popped out of alignment due to a slight shock on the PC case. If the card still does not function, it may mean the motherboard may be damaged.

    For info, A 480 W PSU is O.K. for booting the PC with this gfx card and for basic gfx tasks. It may not be enough for playing a demanding game, though.
  3. Best answer
    It really sounds like your motherboard is broken, try re-seating the card really well again. If its still a no go it's probably broken. You will probably lose about 10 percent performance changing from 16X to 4X.

    Hey suat, what are you talking about. I think maybe you should do a little more reading before giving advise.
  4. Thanks everyone for the comments.

    Previously I had ATI radeon x1650 installed in the PCI-e 16x slot and it stopped working so I assumed the card was bad ...now it seems like its the motherboard itself.

    I didn't update the graphic card driver or do a BIO flash.

    I'll leave the 4850 in the 4x slot for now until I upgrade to a newer Motherboard.
  5. Best answer selected by jobama.
  6. shane799 said:
    It really sounds like your motherboard is broken, try re-seating the card really well again. If its still a no go it's probably broken. You will probably lose about 10 percent performance changing from 16X to 4X.

    Hey suat, what are you talking about. I think maybe you should do a little more reading before giving advise.


    Thank you very much for your kind comment. My info comes from this: "A PCIe card will fit into a slot of its physical size or larger (maximum x16), but may not fit into a smaller PCIe slot (x16 in a x8 slot)." Courtesy of Wikipedia http://en.wikipedia.org/wiki/PCI_Express .
  7. suat said:
    Thank you very much for your kind comment. My info comes from this: "A PCIe card will fit into a slot of its physical size or larger (maximum x16), but may not fit into a smaller PCIe slot (x16 in a x8 slot)." Courtesy of Wikipedia http://en.wikipedia.org/wiki/PCI_Express .


    Hey Suat,

    Sorry I busted your balls on that. Must have been cranky when I typed it.

    If you can flag that advise on Wiki then do it. Its clearly wrong.
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