We show you how to check that the memory installed in your PC or laptop is working correctly. Here's how to find out if your RAM is faulty. See also: Will upgrading RAM make my PC or laptop faster? PC upgrade speed boost.

QUESTION I have recently upgraded my PC's memory by adding an additional two sticks of memory of the same type as the two which were installed when I bought it. Unfortunately, my PC has started crashing a fair bit with the new memory installed.

I have tried re-seating the memory and using different sticks in different memory slots, but I can't make my system run reliably and I'm now not sure which sticks of memory are the new ones.

Is there a reliable way I can test my system to find out where the fault lies?

HELPROOM ANSWER If you have a spare USB flash drive or a blank CD and plenty of time, you can perform a thorough test of your memory using Memtest86+ from

This utility needs to boot from a DOS environment (hence the USB flash drive) and offers a simple menu-driven interface which will allow you to stress-test your RAM.

Follow the Download link at and download either the Auto-installer for USB Key or the Pre-Compiled Bootable ISO, depending on which medium you're intending to use to boot your system.

To make a bootable CD from the .ISO file, use your favourite disc burning software. We've found Imgburn from to work well. (See also: Power surge damage to PC; how to check and fix PC after power surge.)

If you want to make a bootable USB key, you'll need to unpack the auto-installer download and run the utility, selecting your blank USB flash drive. Note that all existing data on the drive will be erased while preparing it for use with Memtest86+.

Now boot up your PC using the disc you just created. The Memtest86+ software should load up and start running automatically. Now you just wait. The testing process will probably take a few hours, depending on how much RAM you have installed, so you may want to leave it running overnight.

Near the top of the screen, in the middle, it will display Test #x, where x is the number of the test currently running. It's generally advised to leave the program running until this gets to around No.8.

If no errors are detected, the problem is probably unrelated to your memory chips. If errors are reported then you may have one or more faulty sticks of memory or possibly one or more faulty memory slots on your motherboard.

You will have to locate the source of the problem by a process of elimination. At this point it would be a good idea to mark your memory sticks in some way so they don't get mixed up again.

Start with the first memory slot and re-test each stick of memory in that slot one at a time, until you find one with errors. If more than one stick reports errors, try testing in a different memory slot.

Also check the specification of your memory modules and ensure that your PCs BIOS is configured correctly for your memory. It's wise to use matched memory sticks – i.e. those that all have exactly the same specifications and timings.

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