I get the POST code error 2b when trying to boot with an Ati HD5870.(graphic card is from ATI not other company)
My system is:Gigabyte GA-EX58-EXTREME, I7-920, 6GB Corsair DDR3 ram and PSU is Corsair 620HX.
I have tried BIOS version F12 and F13Q and still the same error.

I have tested the graphic card on another system and it boots ok. With a 500w noname PSU.

Any help/suggestions?Thank you

P.S. Error 2B means "Invoke video BIOS" (from MB manual)