What Causes Bad RAM Sticks?
Since you can go the entire length of a computer's lifespan without ever working directly with your RAM modules, it's usually only when they begin to fail that you'll realize just how vital random access memory is to a system. While RAM is only tasked with holding onto data temporarily and expediting its return to the computer's CPU on request, memory sticks aren't immune to common faults and system-crashing failures.
1 Soft Errors
RAM modules can experience "soft errors" due to heat, magnetic interference, electrostatic discharge, power surges and flaws so microscopic that they pass quality assurance tests, according to Cisco. Soft errors can cause read and write errors and even crashes, but they are correctable through memory tests or reboots. Two soft errors in the same memory cell could result in a "hard error" in which physical corruption is left behind, according to Dell.
2 Hard Errors
Physical damage creates "hard errors," which can cause hardware or software crashes whenever the affected memory cell is accessed. Unlike soft errors, hard errors are uncorrectable. Hard errors may occur as a result of the memory module experiencing extreme temperatures, incorrect installation, incompatibility or power surges, according to Cisco.
3 Dead on Arrival?
RAM manufacturers guarantee their workmanship, but allow that material defects can still appear in their finished products. Quality assurance testing generally sifts out material defects such as flawed cells or contacts, so it's unlikely but not impossible that you'll discover a fault in a RAM module right after purchasing it. Most RAM manufacturers will replace defective memory.
If your new RAM isn't recognized by your computer, the issue is more likely to lie in its installation than with the modules themselves. Make certain each RAM stick is properly seated in its memory bay and make sure your operating system will accept the amount of memory you've installed. There's a 4GB maximum for RAM on 32-bit Windows installations, while 64-bit installation may allow for up to 512GB. Make sure your BIOS has been properly configured to receive the new memory. Your BIOS may require an update in order to accept your new RAM.