4890 no display and POST error

Whenever I power on my new system I get a POST error that according to my mobo (Gigabyte GA-MA790FXT-UD5P) is a video error, and I get no display whatsoever. However when I put my new video card (Sapphire 4890 Vapor-X) in an older system I have it posts fine and gives out flawless display. When I put that old system's video card (Geforce 6800, also tried a 7200, which also worked) in my new system, it posts fine and gives working display. I tried using two different PSUs (Antec EarthWatts 650 and Corsair HX1000 1000 Watt modular) that I know are good to power my new system (with 4890 in it) and still no display. It seems as though the mobo and 4890 are just incompatible, as they work fine independently, but together I get no display. Are there any known solutions to this? I already tried updating the BIOS to latest (F5), but still nothing.

System specs:
MOBO: GA-MA790FXT-UD5P
CPU: Phenom II 955 @ 3.2GHz (stock speed, stock voltage, stock cooling)
GPU: Radeon HD 4890 Vapor-X @ 870MHz (Stock speed for Vapor X edition)
RAM: OCZ Platinum 1600MHz DDR3 4GB
HDD: WD Caviar Green 500GB
PSU: Antec Earthwatts 650

Thanks in advance
4 answers Last reply
More about 4890 display post error
  1. you are plugging in the extra power plugs into the graphics card arent you?
  2. montyuk said:
    you are plugging in the extra power plugs into the graphics card arent you?


    Yes, I'm using both PCI-e 6 pin cables. I aslo went through the checklist evon posted, and still nothing. At this point I'm thinking of getting a new mobo altogether and ditching gigabyte for an MSI or ASUS. Any thoughts for last ditch efforts to get this working?
  3. There are some known problems with the Sapphire Radeon HD 4890 1GB Vapor-X cards. I actually tried upgrading to one but the first one I got was:-

    - 100% fan speed and no signal more than 50% of the time

    - Second one I got (replacement) was BSOD 3 out of 4 times and only worked once


    My specs

    Intel Q9450 Yorkfield @2.66ghz stock
    Gigabyte GA-EP45-DS3L (haven't updated BIOS)
    4GB DDR2 RAM
    Antec True Power II 550W PSU

    They actually at the shop told me to update to latest BIOS too, I didn't and just got a refund on the card.

    Check out the Sapphire forums

    http://www.vgaforum.com/forumdisplay.php?s=09a032fb2e8fcb3eeb41c0f5bf38bda9&f=4

    LOTS of people having problems with the 1GB Vapor-X. Had I come across this forum before my purchase, I would have NEVER purchased this card. It's a shame, because it has a bit of an overclock and very nice cooling, but unfortunately, there is a problem with that line of card.

    Personally, I'd stay away from it.

    Hope this helps
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