i had the same issue- could not get it to post for 2 days- here is what i did-
remove mobo, remove cmos battery and jumper, reseat memory, i had to do this for like 2 days straight. Literally it would not post no matter what.
here is why and what the problem is- the cpu speed by default in the bios is 500mhz. You need to get lucky and get it to post and immediately go in and change that number one.
I thought that would fix it. 3 more hours it still would not post. here is what i dis next. At the next time i got it to post i changed the SDRAMtiming settings from its default to of 8.5-10ns to medium. After that, it posted every single time.
weird huh?