HP Workstation x2000 hp workstation x2000 - Technical Reference and Troublesho - Page 50

System Board Memory Controller Hub (82850) overheating. RDRAM devices may be in one of three power-management states: active, standby or "nap." The MCH implements the RDRAM nap mode. Two queues are used in the MCH to control power consumption: the A queue contains references to device pairs that are currently in the active mode while the B queue contains references to devices that are in the standby mode. This means that all devices that are in neither queue are in standby or napping. The A queue can hold from 1 to 8 device pairs, while the B queue can be configured to contain between 1 and 16 device pairs. This allows power consumption to be tuned. The MCH also implements a mode in which all devices are turned on and it is assumed that the system will provide adequate cooling. This means that all devices that are in neither queue A or B are in standby mode. One fail-safe mechanism is supported that protects the RDRAM devices from thermal overload. This mechanism polls the thermal indicator bits in the RDRAM devices themselves. When the mechanism is activated, the MCH immediately exits the "all devices on" mode and reverts to whatever queue mode has been programmed by system software. Dual Rambus Bus The Dual Rambus bus is comprised of 16 x 2 bits of data information, and eight bits of Error Correcting Code (ECC). The bus is connected to the RIMM memory slots and to the MCH chip so that the system supports two Dual Rambus channels (A and B). Both channels run at 300MHz or 400MHz, supporting as many as 32 Rambus devices per channel. The maximum available data bandwidth is 3.2GB/s at 400MHz. The configuration of both primary rambus channels must be symmetrical. The memory configuration on channel A must be identical to the memory configuration on channel B. This means that you must install the memory in identical pairs. RIMM Memory Slots The HP x2000 Workstation has four RIMM memory sockets for installing two or four RDRAM memory modules: • RIMM A1 • RIMM A2 50 Chapter 2