From compaq Forums newsgroup: "Press "F10" at POST to enter BIOS setup. When BIOS setup menu appears, arrow over to Advanced, then, arrow down to APIC Table. Check to make sure it is set to "Full Table Mapped". You can use the right arrow key to scroll through settings. At this point save settings and BIOS should be set properly for multiple processor support.
If the problem persists, then you will need to use the Compaq NTSSD to upgrade the NT Kernel to multiple processor support. You can do this by running the NTSSD from smartstart and selecting uniproccesor, then, upgrade. You will need your service pack CD and when it asks for Compaq Media, select ignore and type in the path of your CD-ROM drive pointing to the i386 directory of service pack. It will find the files it needs for multiple processor support and update them. At this point, it should turn green and say multiple processor. You should now have both processors showing up in NT on the next boot up."