RAM Kharab Hai Ya Nahi? MemTest86 & Windows Memory Test Full Guide

Recognise the Symptoms of Bad RAM

Faulty memory rarely dies in one clean moment — it misbehaves first. The classic signs are blue screens with changing stop codes, programs crashing randomly, files corrupting on copy, the PC freezing under load, or failing to boot with beep codes. When the symptoms look random and keep changing, RAM is one of the first parts to test, because a bad stick corrupts everything that passes through it.

Quick Test — Windows Memory Diagnostic

Windows has a memory tester built in, so the first test needs no download. Press Win + R, type this command and press Enter:

mdsched.exe

The Windows Memory Diagnostic window opens with two choices: Restart now and check for problems (recommended), or Check for problems the next time I start my computer. Save your work first — the PC restarts and the test runs before Windows loads, outside the operating system, so it can check memory Windows itself is not using.

At Boot: Set the Test and Pass Count

While the blue test screen is running, press F1 to open its options. You get three settings: the test mix (Basic, Standard or Extended — Standard is the default and fine for a first run; Extended is the deepest), the cache setting (leave it at Default), and the pass count — how many times the whole test repeats. The default is 2 passes. More passes catch more borderline faults, so for a suspected stick, raise the count and let it run longer.

Read the Windows Test Result

When the test finishes, the PC boots into Windows and the result appears as a notification: either no memory errors were detected, or hardware problems were detected. If you miss the notification, open Event Viewer → Windows Logs → System and look for the source MemoryDiagnostics-Results. "No errors" from this quick test is a good sign, but it is not the final word — the Windows test is the lighter of the two, which is why the video goes one step deeper with MemTest86.

Deep Test — Make the MemTest86 USB

MemTest86 by PassMark is the long-standing standard for serious RAM testing. Download it from the official site, memtest86.com — the free edition is enough for this job. The download includes a USB image-writing tool: run it, select your USB drive, and it writes a bootable MemTest86 pendrive. Then restart the PC, open the boot menu, and boot from that USB. MemTest86 runs entirely outside Windows, so it can test practically all of your RAM.

Run MemTest86 and Watch the Errors

MemTest86 starts testing automatically and works through its full set of test patterns. By default it runs 4 passes — on a typical system that takes a few hours, and for a machine that crashes randomly it is worth letting it run even longer, or overnight. Keep your eyes on the Errors counter: healthy RAM finishes with zero errors. There is no "acceptable" number — even a single error means the memory is not reliable.

Find the Faulty Stick and the Verdict

If errors appear and the PC has more than one stick, test them one at a time: shut down, remove all but one stick, and run the test again. A stick that errors on its own is the faulty one. Also swap the same stick into a different slot — if the errors follow the stick, the stick is dead; if they stay with the slot, suspect the slot or motherboard. Before condemning a stick, reseat it firmly and make sure the contacts are clean, since a loose stick can error too.