4 Good sticks of ram and 4 good slots on MOBO, but only 8 of 16 shows up in bios and windows.

I have an Asus P8b75-v motherboard and 4 sticks of g-skill sniper ram. they are 4 gigs each and all the same type. Until recently everything was fine, but suddenly only 8 of 16 was being used. I figured one of the 2 older sticks were bad so i had them RMA'd. I got the new replacements yesterday and put them in and still no 16. After extensive testing i have determined with absolute certainty that all 4 sticks work and all 4 ram slots in the motherboard function. Yet for some reason I cant get more than 8 gigs to work. The bios is updated to the most recent, and everything was working fine until a couple weeks ago. Im completely confused and would really appreciate any help.
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  1. I assume by "determined with absolute certainty" it means something like using Memtest for at least 8 passes.

    I had something similar occur. My own fix was... to reinstall the RAM again and again, until Windows recognised all the RAM again. (Oddly, BIOS and other monitors could see all the RAM but not Windows.) I just put it down to a quirk.
  2. First find which aren't working. Then look for bios updates as they often include memory stabilty fixes. Then try them again with the latest bios. If still fails then the RAM may be bad so test them only in bank 0. If nothing works then RMA the bad RAM. If they do work you may need a new motherboard. Your motherboard has lots of bios updates.
  3. Guys feel free to actually read what i said before responding. The ram works, and the slots on the mother board all work. The bios is updated.
  4. Ram is sold in kits for a reason.
    A motherboard must manage all the ram using the same specs of voltage, cas and speed.
    Ram from the same vendor and part number can be made up of differing manufacturing components over time.
    Some motherboards can be very sensitive to this.
    This is more difficult when 4 sticks are involved.
    That is why ram vendors will NOT support ram that is not bought in one kit.

    What to do?

    If there are some bios updates, they often address such issues as ram incompatibility.
    DO NOT flash the bios on speculation.
    A failed flash can be nasty or impossible to recover from.

    Try increasing the ram voltage in the bios.
  5. What RAM frequency is it, and what chipset is the motherboard? Does this issue appear with XMP profile(s) only, or at the JEDEC standard (= you haven't touched any settings or enabled any XMP profile)?

    EDIT: Checked the mobo and it's the B75 chipset, supporting 1600/1333MHz.
    Ignore my post above :p
  6. Nick Blowfeld said:
    Guys feel free to actually read what i said before responding. The ram works, and the slots on the mother board all work. The bios is updated.

    Are you talking about showing in bios or windows? If its bios and the its updated then you may need to reset the bios. Dont overclock or set XMP.

    If its windows then check your drives. Corrupt or unsigned driver issues may cause the issue. Also here is a few things to try in msconfig, bios, and others.
  7. Its not showing in Bios or Windows. What do you mean by reset the bios? Ive dicked around with the settings a whole bunch and no matter what i try i cant get more than 8 gigs to show. But im certain all the slots are working and all the ram is good. Is there something that could be wrong with the mobo thats keeping it from recognizing the 16 other than the ram slots?
  8. Best answer
    So, what if you listed the steps you've taken to troubleshoot. To include programs used, methodology, and for how long, instead of being short tempered and rude. You want help but you don't want to take the time to list the steps you've taken. We can't help you unless we know what you've done, otherwise people will continue to say "try this" or "try that."

    This will help people here determine where you're at in the process and to suggest other things. They might also point out different ways you can do something you've already done to help you more.
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