8.4GB NT Install Barrier

Have a HP 8750C Pavilian I want to use as a test server. Every time I install NT 4.0 I am limited to 8.4GB. I have low level formated it (the complete 30G), and I have changed CMOS/Bios to reflect the correct LBA and the correct heads/cyl. I have NOT done a high level DOS format though, I have been letting NT format and partition it during install. One note during install, the mass storge devices detected during install does not include the hard drive, only the CDs. What am I missing? Thanks in advance everyone.