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PCIe 3.0 (AMD 7770) not compatible with old motherboard?

Hi all,

I have a Gigabyte P35-DS3L motherboard that is PCIe 1.0, and I just tried to upgrade my 8600GT video card to an AMD 7770. I have a new Antec Earthwatts 650 power supply to support the 6-pin aux power and I get a greenlight on the video card when everything is plugged in.

However, when I try to boot the computer I get 1 long, 2 short beeps at startup and no video displaying. I looked up the beep code and that typically seems to be related to a video card problem.

When I switch back to my 8600GT, everything works fine. I can't see anything that could possibly be wrong with the hardware arrangement, except that the mobo may not support the new card.

I know PCIe 3.0 is supposed to be backwards compatible, but could I be unlucky with this particular combination? The last revision of the BIOS (which I have installed) is June 2009, which is a long time ago, and the documentation makes no mention of adding PCI 2.x support.

Does anyone have this motherboard and know of alternative upgrades that might work in the same price range?
6 answers Last reply Best Answer
More about pcie 7770 compatible motherboard
  1. Best answer
    it could be your video card. pci-e 3 cards like the 7770 work fine in older 2.0 or even 1.0 boards.
  2. Well technically speaking PCI-e 3.0 cards are compatible with PCI-e 1.0 slots, but reality could be different. For example, PCI-e 2.1 cards are supposed to be 100% compatible with PCI-e 1.0 slots, but in fact they are not since there have been a decent number of complaints about incompatibility issues.

    I have not heard of any incompatibility issues of PCI-e 3.0 graphic cards in PCI-e 1.0 slots, but most gamers in this forum do not have such an old motherboard anymore.
  3. You're right that very few people have this motherboard still, so it's been difficult to try and find compatibility stories with newer GFX cards. Maybe I'll compromise and get a GTX 550 Ti. Even though the performance isn't as good as the 7770, it's PCIe 2.0 and I've at least heard of people successfully using the combination.
  4. if you overly concerned about the PCI slot, maybe look at the 560 SE or the 560 for a few bucks more.
  5. Best answer selected by Turbofrog.
  6. Turns out that indeed the card was defective (buyer beware of Open Box specials, I guess). Replaced it and the new 7770 booted up no problem.
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