High Speed SDRAM Memory Module [Speed, Quality and Reliability Challenge] Delivering a high speed SDRAM memory module that remains stable overtime and sustains temperature variations is a difficult challenge for any company involved in this design, manufacture and distribution. Newer blazingly fast CPU speeds and high speed data buses crossing 100 Mhz /133 Mhz has increased the necessity to select the SDRAM chip based on quality, compatibility of the memory board, reliability and testing of the overall assembly of memory module. Earlier slower system bus speeds allowed considerable margins in the design. Now tighter specs in timing and signal trace lengths are demanded from memory subsystems to squeeze more performance out of today's systems. Memory and I/O speeds are being boosted, which also necessitates keeping the entire system in balance. As a result, increasing memory bus speeds requires stable SDRAM memory modules capable of delivering the speed and reliability to the CPU in order to improve overall system performance as much as possible. The Illustration below summaries some of the features of a SDRAM Memory Module capable of operating at a high clock speed, that must be incorporated to deliver stable I/O from the main memory to the system CPU. Typical Problems with Memory. . . The table below lists typical problems found with memory as a result of inadequate qualification testing, poor manufacturing and design techniques and nonexistent quality control.   This problem...   Causes this result... DRAMs not adequately grounded; copper traces poorly placed and routed Separate power and ground planes are required to avoid poor DRAM performance due to noise and cross talk, resulting in increased possibility of bit errors. Broken or missing decoupling capacitors. Memory module may be functional at the time of purchase but later DRAM is vulnerable to damage from power supply spikes and surges. DRAMs sensitive to unstable signal from chipset during don't care states Single, double or multibit errors, a common problem intrerfacing 100 Mhz SDRAM with high speed CPUs Serial Presence Detect (SPD) improperly configured or not configured at all. Miss match occurs when trying to put DRAMs on the "Generic third party memory board" this will misinform the processor of the speed of available memory. Using incompatible DRAMs Systems failure due to timing errors and other miscellaneous consequences. Improper routing of module board shape resulting in misaligned connectors. Electrical short causing burn damage to server at module/memory slot junction. Poor-quality solder joint Long-term failure after continuous operation in high-temperature environment.

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