SDH, you are very experienced with setting up and increasing system performance on HP Workstations, but I have some comments for others.
- A Z400 with 6 DIMM slots and boot block date 11/10/2009 is a "revision 2" motherboard. This system supports both 55xx and 56xx CPUs.
- The "revision 1" motherboard had 4 DIMM slots and a boot block date of 01/30/2009. This system supports only 55xx CPUs.
HP never called the different Z400 boards "revision 1" or "revision 2". However, on this forum, these names are used a lot. My reply is to caution others who read other threads about the 2 "revisions" that a Z400 with the older 01/30/2009 and 4 DIMM slots will not work (or be very unstable) with 56xx CPUs.