You shouldn't need an active adapter and DP->DVI will work. DP is designed to be backwards compatible with single link DVI. I have an asus board with the pciephy-based DP port and it works fine with both DP directly and DVI via a passive adapter. It sounds to me like your board may have issues if neither the open or closed driver is able to use the DP port. Is it possible that your DP->DVI adapter is bad? Did changing any of those bios options I suggested help?
I know it shouldn't need it, but I understand that DVI requires a clock signal that may or may not be available on a DP. Typically under these circumstances it should be, but board maker may have their own ideas.
In any case, its a no-go with an active adapter. Both the passive and active adapters are tested and confirmed working on an asus board.
So that leaves two possibilities; defective bios, defective board.
Guess I'll wait for the manufacturer to get back to me.
Well, I'll tell you the way I was looking at the thing;
The onboard 4290 is *lots* of power for my needs. The 1090T is really where its at since I am far more interested in fast compilation. The options I had in terms of chipsets were 880, 890GX, 890FX in order to properly take advantage of the CPU and some nice 1600 MHz DDR3. The FX was far more money and only really amounted to having more PCIe lanes -- great for multi-GPU, which I have no interest in, GX has enough lanes left over for other things I might eventually want to add in, like a RAID card. The other chipsests all had integrated GPU, so I was going to have an integrated anyway... why not get one that will do everything I need?
Nv is totally out of the question in terms of new purchases. I've been burned enough times by them that they'll have to make some radical changes before I'll look at them again. I've lost way more hair dealing with their blob than with this.
At the moment, I do have an nv in the machine. One I was really hoping to ditch. If you look back a few posts, you'll see that I've resorted to a 7800gtx. At least it works ok with nouveau, but it adds a lot of heat and sounds something like a vacuum cleaner, so I'll probably be looking to a 4350 or 4550 with passive cooling if ECS can't help me with this onboard 4290.
Aside from the display issues, I am very satisfied with the machine. Had a few lockups when the memory timing was set to automatic, but manually set to its spec (1600 MHz 7/7/7/24) and its totally stable and the thing is wickedly fast.