4GB single stick won't POST.

I am building a gaming rig, I have a single stick 4gb DDR3 1333 and it will not post, I have tried separating the motherboard from the case, however, it WILL Post and boot with 2gb with the 4gb taken out. This motherboard is supposed to support up to 8gb of ram with two slots.

With the 4GB stick, the mobo won't post, or even beep. Completely Silent.
6 answers Last reply Best Answer
More about single stick post
  1. General:
    Some MOBO's require the Channels to be EQUAL in size, and some MOBO have a CAP on the Density per DIMM slot.

    Meaning IF your MOBO has 4 DIMM slots and its' maximum is 8GB then 8GB/4 DIMM = 2GB per DIMM slot.

    ASUS M5A78L-M LX -
    2 x DIMM, Max. 8GB, DDR3 1866(O.C.)/1600(O.C.)/1333/1066 Hz ECC, Non-ECC, Un-buffered Memory
    Dual Channel Memory Architecture

    1. Supports 2x4GB
    2. Try the 4GB stick in the DIMM slot closet to the CPU
    3. Possible problem as stated is Channel A (NOT Equal) Channel B

    The Manual is in Spanish, French and German - I know English...
  2. I see, I have tried placing the stick closest to the CPU, still doesn't boot, I don't want to risk getting another 4GB and it still doesn't work.

    Because a single stick of 2gb worked fine without anything in the second slot.
  3. Best answer
    IF you used ONLY the 4GB as (CPU: | 4GB | blank | ) and it's failing to post then one of two likely suspects:
    1. Bad RAM
    2. BIOS problem

    To remedy a BIOS Problem:
    1. Clear CMOS, use Jumper method and to verify successful CMOS procedure the Date and Time will be reset. In the BIOS Load Defaults and set both Date and Time, Save & Exit = Yes, and reboot. See -> How To Clear CMOS properly.
    2. Failure remains, then Flash the BIOS - use the ASUS EZ Flash 2 method:

    EZ Flash 2 is a built-in App to allow the BIOS to be upgraded and USB Flash Drive is the storage for the BIOS ROM file to be stored/accessed from with BIOS EZ Flash 2. The USB Flash drive must be formatted in FAT-32.

    Link ->
    Video ->

    Use Version 0602

    3. Failure remains after BIOS update, then it's safe to assume the 4GB stick is BAD. Return it.

    If the 'Goal' is 8GB then IMO the following kits:
    QVL = G.SKILL Ripjaws Series 8GB (2 x 4GB) DDR3 1333 CAS 7 F3-10666CL7D-8GBRH -
    ref -

    G.SKILL Ripjaws Series 8GB (2 x 4GB) DDR3 1333 CAS 9 F3-10666CL9D-8GBR -
    ref -

    Either will work, sure the CAS 7 are indeed faster but $15 worth that your call, in gaming maybe 1~2 FPS faster.

    Q - WHAT CPU do you have installed???
    Q - WHAT BIOS version is installed?

    If the CPU isn't supported via the current BIOS the 'CPUID' will dummy-down the CPU and all sorts of 'fun' things, like this, can happen.

    If you don't know your BIOS version then either boot into the BIOS and look or run CPU-z and look at the 'Mainboard' tab -
  4. So I tried the 4GB stick on 2 separate motherboards, and it looks like it's dead, going to return it for a different brand.

    Thanks for the replies.
  5. Do one of two things...

    1. Leave the computer off for about five minutes with the RAM on it.

    2. Switch RAM slots. When you switch slots, turn the computer on, then back off for about five to ten minutes. Worked for me.
  6. Best answer selected by Anjo206.
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