Modules failing in PCs, but passing SIMCHECK units

Some modules seem to fail in a certain computer and yet they pass the test on the SIMCHECK system (or any other memory tester). This application note discusses the possible reasons for such mismatches.

Modules failing in a PC, but passing SIMCHECK even after a program update, may in fact be good modules after all. Today's systems require strict timing parameters that must be observed before installing and using the proposed memory devices. If the device has a slower speed than the motherboard is expecting, an expected error will occur, whereas installing the same memory component on a different system will cause no error. Such a module may also work in a slower system.

An additional aspect, is to realize that not all modules are drop in replacements for every system board. Some modules have key differences in wiring that will prevent them from working on certain system boards. Before installing the memory device, you should consult the system manual for any information on the exact module type required (i.e. sizes supported, mode type, etc.).

Another possible problem that would cause such a situation would be a module pattern sensitivity problem. This is one of the most complex problems that could occur in a memory device, making the testing of these components that much more complicated. The number of possible memory patterns for a typical 256K chip is an astronomical figure [256,000 x 2^256,000], therefore running a complete exhaustive pattern test on a modern device would be theoretically impossible, even on multi-million dollar test equipment.

Our R&D department is looking forward to try and verify and correct problems occurring with memory devices if you should decide to send samples of modules that are not supported in our firmware, or otherwise causing problems that are not detected.

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