2–4 Features

Power Requirements

2.1 Power Requirements
The AlphaPC 164LX motherboard has a total power dissipation of 100 W, excluding
any plug-in PCI and ISA devices. Table 2–3 lists the power requirement for each dc
supply voltage.
The power supply must be ATX-compliant.
Caution: Fan sensor required. The 21164 microprocessor cooling f an must have
a built-in sensor that will drive a signal if the airflow stops. The sensor i s
connected to motherboard connector J18. When the signal is generated,
it resets the system.
2.2 Environmental Requirements
The 21164 microprocessor is cooled by a small fan blowing directly into the chip’s
heat sink. The AlphaPC 164LX motherboard is designed to run efficiently by using
only this fan. Additional fans may be necessary depending upon cabinetry and the
requirements of plug-in cards.
Table 2–3 Power Supply DC Current Requirements
Voltage/Tolerance Current1
1Values indicated are for an AlphaPC 164LX motherboard with an Alpha 21164 microprocessor
operating at 600 MHz, with 64MB SDRAM, excluding adapter cards and disk drives.
+3.3 V dc, ±5% 5.0 A
+5 V dc, ±5% 14.0 A
–5 V dc, ±5% 0 A
+12 V dc, ±5% 1.0 A
–12 V dc, ±5% 100.0 mA