I have a Gateway SX2802 that comes with onboard Intel GMA X4500 video. I have added a PCIe Radeon HD5450 video card which works great.
Ideally, I want to run 3 displays (2 from the HD5450) and 1 from the onboard video. Unfortunately, I have tried every combination of bios settings and I can't seem to get both video sources functional at the same time.
Yep, It just cant work, because the display can only come from, the motherboard, or the graphics card, Unfortanetly only 1 can be used so in your case the Graphics card, but you can buy a graphics display splitter, so you can use several monitors with the graphics card.