systemboard lockup of windows

I PURCHASED (2) motherboards. I jumpered them according to specs and they lock up in Windows ( after about 2 minutes). It does it with a 90mhz, 133mhz and 166mhz processors.
What am I doing wrong?? I purchased them from
a computer show vendor. Is there anyway I can get some warranty help or troubleshooting assistance. The’re P5F76 & P5F85 boards.