IBM 847651U Handbook - Page 131

Working with memory modules Install DIMMs with a maximum height of 6.35 cm (2.5 inches). Use only 3.3 V dc 100 MHz SDRAM DIMMs. Do not mix registered and unbuffered DIMMS. If you use registered DIMMs, you must remove all unbuffered DIMMs from your server. A mix of registered and unbuffered memory prevents the server from completing startup, and results in a 1-3-4 error beep sequence and a blank screen. Each memory connector supports a maximum of 256 MB of memory. However, the maximum amount of unbuffered system memory your server supports is 384 MB. Your server supports up to 768 MB of registered memory. To enable ECC, all DIMMs must be ECC; therefore, install only ECC DIMMs. If you install nonparity (NP) DIMMs, the server will not power up, and POST memory error code 164 will be displayed. For additional information on error code 164, see "POST message table" on page 169. If you are installing DIMMs of different sizes, for optimum signal quality, install the DIMMs with greater memory capacity starting with the connector closest to the edge of the system board (DIMM 2). After installing or removing a DIMM, you must save the new configuration information using the Configuration/Setup Utility program. See "Using the Configuration/Setup Utility program" on page 39. For more information about the DIMMs that your server supports, go to the following World Wide Web address: http://www.ibm.com/pc/us/compat/ Memory configuration When you are adding or removing memory, a basic rule to follow is to fill each system memory connector sequentially, starting at DIMM 2. For optimum signal quality, install the DIMMs with greater memory capacity starting with the connector closest to the edge of the system board (DIMM 2). Chapter 4. Installing options 97