Motherboard Problem.

I have a strange problem or should I say a strange fix. My computer
is
"handcrafted" shall we say. I bought an AGP X1600 pro. My motherboard
is a AX4SPE MAX (aopen) There is no on-board graphics. If I put in a
different graphics card other than the x1600 pro my computer boots up
and works just fine. If my x1600 pro is put in another computer it
works fine. If the X1600pro is in my computer it won't even post...
but i found out.. IF i turn on my PC without the graphics card in
it.Then put in the X1600pro and hit the reset. It works just fine!
(YES, I just said that and i've done it for a good six months at
least.) I was just wondering WHY? Is there a fix short of buying new
hardware? Are my devices not compatable?(they seem to work just fine
together) The power supply fully supports the size of graphics card.
I've even tried another power supply. The computer won't even post
when the x1600 pro is in it. Its just like when you got a bad
motherboard. I've tried a new motherboard too. Same problem. (In
hindsight i should have bought a different brand motherboard). So...
Should I buy another graphics card? How do I know its won't happen
again. The Graphics card that works just fine with it is OLD. Any
insights?

Thanks in Advance.