Not all of installed RAM is seen by NT

This is an older system, DECpc XL560 (60Mhz P2).
I am trying to give it a little life by max’ing out the memory. I have installed 6x32MB in the available 72 pin SIMM slots which is the max configuration supported. The RAM modules are FPM, 70ns, parity with (I think) a 2K refresh rate.

When booting up the BIOS sees all 192MB of installed RAM. Windows NT SP6a sees only 65MB. If I install 64MB or less both the BIOS and NT see the same amount. This is not being caused by a /maxmem switch in theboot.ini file (see microsoft kb article 108393).

Is there some other setting (registry?) that could be causing this limitiation? Is it possible that the memory modules can be seen by the BIOS but not NT? Any ideas?

Thanks!