My P5Q Pro Won't Recognize 4 Sticks of Memory

Written by ken white
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My P5Q Pro Won't Recognize 4 Sticks of Memory
Memory issues require specific steps to diagnose. (ram 2 image by PeteG from

Modern motherboards like the Asus P5Q Pro normally have four slots to place random-access memory (RAM) modules on the motherboard for use by the operating system. It is, however, very important that the RAM modules meet the specifications of the motherboard for type, size and module configuration. Any deviation can cause the RAM to be unrecognized by the motherboard or the operating system and may cause errors while using the computer. You may also encounter bad memory modules and will have to troubleshoot the memory to determine which modules are bad.

Skill level:


  1. 1

    Ensure that you are using the proper memory modules for your Asus P5Q. This motherboard requires DDR2 Dual-Inline Memory Modules (DIMMs), with a maximum memory capacity of 16 gigabytes (GB). It must be non-ECC (also known as nonparity) and unbuffered memory. The speed of the memory is not critical, and the motherboard will handle DDR2 memory at speeds of 1300, 1200, 1066, 800 or 667 megahertz. The P5Q Pro will not work with DIMMs that are made up of 256 megabyte chips or smaller. If your memory modules do not meet this requirement, you must replace them.

  2. 2

    Check the motherboard BIOS (basic input/output system) information to determine if the full memory capacity is available to the motherboard. This information usually appears on the screen during the Power On Self Test (POST) before the operating system loads, or can be accessed by opening the BIOS by pressing the "Delete" key while the POST information is on the screen. On the main BIOS screen, used the arrow keys to move down to "System Information" and hit "Enter." The usable size of the system memory will be displayed.

  3. 3

    Run a 64-bit operating system such as Windows 7 64-bit if your memory size is 4 GB or greater and your motherboard recognises all installed memory, but the operating system does not recognise it. Operating systems like Windows 7 32-bit will not recognise more than approximately 3 GB of memory, regardless of how much memory you have installed. To take full advantage of larger memory size, upgrade your operating system to 64-bit.

  4. 4

    Check to ensure that all of your memory modules are properly seated in the slots. Power down the computer and unplug it to remove power to the motherboard. Open the case to access the motherboard. Press down gently but firmly on each of the four memory modules. The retaining clips on either end of the slots should be snugly hooked to the notches at the ends of each DIMM. If you are unsure, remove the memory modules and reinsert each module, pressing down until you hear the retaining clips snap into place.

  5. 5

    Test the memory modules and memory slots two at a time. Remove the four memory modules, insert two of them in the first and third memory slots, plug in the computer and turn it on. If the BIOS and operating system recognise both at full capacity, shut down the computer, unplug it and remove the two DIMMs. Take the other two modules and insert them in the second and fourth memory slots, plug in the computer and turn it on. If during the process of testing the memory modules you see half of the expected memory capacity, that indicates that you have a bad memory module or a bad memory slot.

  6. 6

    Check each of the memory modules individually, following the same process. You are specifically interested in the memory modules, because if a memory slot is bad, it is not user-replaceable and you will have to replace the motherboard. Using the same process, test each DIMM individually in the first memory slot. If one of the modules is bad, the computer will not boot or you will get an error when you turn on the computer. If you have a bad memory module, you must replace it.

Tips and warnings

  • Static electricity can damage electronic components. Always ground yourself before working inside a computer.

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