Try resetting CMOS either through a jumper ( if there is one) or by removing the battery and reinserting it. Last weekend I tried to set up an ASUS p4b266 + P4 1.8 system and had the same problem. Couldn't get a video signal to save my life, and it wasn't the video cards either. Returned the board to the computer show vendor and he said I should have reset the CMOS, but he wouldn't admit that this was a common problem with the ASUS board. Ended up getting a P4T-E and RDRAM instead cause it was my wife's system I was upgrading and I didn't want to hear any complaints, if you know what I mean. I know your board uses the SIS rather that the Intel chipset, but the CMOS reset may be worth a try. Good luck and let give us some feedback if you get the problem resolved.
