Towers and Racks 249Towers and Racks#5156 Redundant Power and CoolingThe #5156 adds an additional 575-watt power supply for redundancy and an additionalcooling fan to the #5075 PCI Expansion Tower, which attaches to Models 270 and 820.Marketing configurators default, on a Model 820, to a #5156 for any added #5075 when thesystem unit contains a #5155. If a #5155 (575-watt power supply) is ordered as an MES to anexisting Model 820, default one #5156 for each #5075 present or ordered. The #5156s arenot mandatory and can be removed from an order.#5078 PCI Expansion UnitThe #5078 is a “top hat” that installs on the top of the #9079 Base I/O Tower (Model 840 only)or #5074 PCI Expansion Tower and allows PCI IOAs to be installed. The #5078 may beordered with a #5074/#9079 or added at a later time. If the #5078 is ordered with the#5074/#9079, the #5074/#5079 ships with the #5078 installed.The #5078 includes the #9691 bus adapter or the #9739 optical bus adapter to provide theHSL interface to the system. The configurator adds the #9691 to the order automatically.The #5078 contains two buses. PCI cards are supported using the same rules as the#5074/#9079. Internal Disk and removable media devices are not supported in the #5078.The #5078 may be on the same HSL loop as the #5074/#9079 it is mounted on, or it may beon a separate HSL Loop.Select any two of the supported HSL cable features for the first or only tower of an HSL loop.For additional towers on the HSL loop, select one HSL cable per tower.A list of the supported HSL cables is shown in a table on page 271.When the #5078 is on the same HSL loop as the #5074/#9079 on which it is mounted, the#1461 3m Copper HSL cable is sufficient.Note: The #1462 15m HSL cable can only be used on HSL port A1 of the Model 820 todirectly connect a #5033, #5034, or #5035 Migration Tower I.Select one of these SPCN cables per tower:• #1463 - 2m SPCN cable• #1464 - 6m SPCN cable• #1465 - 15m SPCN cable• #1466 - 30m SPCN cable• #0369 - 100m Optical SPCN cable• #1468 - 250m Optical SPCN cableThe #5078 PCI Expansion Unit supports four 32-bit and seven 32/64-bit PCI slots.
