Closed Solved

Missing 2gigs of RAM

Hey guys,

I am trying to squeeze as much life out of my old gaming pc as I can. I recently installed 2x2gigs of Ram, making it 8gigs total, but for some unknown reason it says I only have 6 gigs usable. I really need at least 1 more gig to make everything run smooth during times of heavy use. So where has the 2 gigs gone?

I think one possible solution, is a bios setting or value needs to be enabled or tweaked.
I enabled the Memory Remap Feature and it says 8gigs are installed, but still only 6 gigs are usable:

The other option is, I have to update the BIOS of the MOBO?
Version 0613 - (
"6. Improve memory compatibility while 4GB memory plugged"
This step somewhat scares me, as I've never done this and it may turn my pc into a brick, and good chance that it won't solve the problem.

Or maybe it's just a compatibility issue with the RAM I got and the old MOBO?

Any ideas?

Current System:
Intel Core 2 Quad Q6600
Asus P5B-VM
8gb RAM
ATI Radeon HD 5770 (HD 7850 coming soon)
256GB SSD Crucial M4
650w PSU
HAF 912
Windows 7

MOBO Manual:

17 answers Last reply Best Answer
More about missing 2gigs
  1. I'm assuming the RAM you just bought does not exactly match what you already had installed, correct? Same CAS latency? Proper slots (original RAM in the two "A" slots and new RAM in "B" slots)? Try adding each of the new ones one at a time, one of them could be bad.
  2. Not sure how to check the CAS latency, but I will add each one separately and see if one of them is defective. Thanks.
  3. Programs like CPUZ will show the information for all RAM slots, or if you knew exactly what RAM you used before, look at the specs online vs. the RAM you just bought. There are notes in the manual that mention using same latency and how to arrange it in slots and certain limitations for compatibility.
  4. Holy Cow, you're right! The CAS# latency don't match, the older ram is 5.0 and the newer is 6.0. So this is than the most likely culprit for the missing memory? Even though the newer cards is better, has more bandwidth, etc.?

    I looked up how much the older "2.0GB Samsung Original PC2-5300" go for, and it would cost me $90 to replace the 2x2gigs :o. Eh.. $90 for extra ~1.xx gig doesn't seem worth the price tag, especially for an outdated mobo.

    Is it possible to lower the CAS latency on the newer RAM, making it match the old and perhaps become more compatible..? Or maybe just update the bios and hope for the best?

    CPU-Z RAM:
  5. When it comes to RAM you just simply have to use identical units! It may goes to manipulate and downgrade the new ones so they match your old but that would at least in my mind become very instable and perhaps in the end cause physical damage to your MB, CPU and Chipset. You have to diside whats most expensive - taking short cuts and maybe fry the rig so you cant use it at all, or spend some money and get two old but identical RAMs so you got a total of 8 GB RAM to play with. I´m no expert in this case but one thing I for sure have learned is NEVER EVER mix two different RAMs or the same brand but different series of it! Consulting first your MB manual so the board dont automaticly choke itself by inserting more RAM, and how much RAM the board itself is limited to.

    This is exactly what I try to tell people whos buying a new PC: always make sure to maximize the total RAM zize from the beginning even thus it costs money!

    Folks that think "I can always get more RAM later if I need it because I cant afford that cost right now when I want to get that beasty GPU" is deciving and fooling themself because after a year those specific serial numbers of RAMs does not longer exist on the market and there you stand with this un-wanted choise of yours!

    No hard feelings or any personal hacking on you as a person but for your own sake think about this before you buy a new PC :-)
  6. lol thanks Darth, I wouldn't want to damage the mb/cpu

    The newer RAM i believe is cheaper.. like $25, so I guess I could get 2 more of the new ones and replace the older RAM instead, right? Although, I will be pissed if it still reads 6 gigs usable or less, because of some weird comparability issue with the newer RAM and the older mb.
  7. Forgot to tell that the latest BIOS driver (at least for my ASUS Sabertooth MB) is v.1304 and you have to flash BIOS with it, its not an ordinary update thing. Tried to flash it with a USB stick but failed every time with the word "Boot block in file is not valid". Use instead ASUS own tool for searching and flashing BIOS that comes with the motherboard DVD.

    The older RAM is 1.8 V and 333 MHz
    The newer RAM is 1.8 V and 400 MHZ

    Can't I just go into the BIOS and configure each RAM to have the older RAM values.
    Change each RAM to:

    CAS# Latency: 5
    RAS# to CAS#: 5
    RAS# Precharge: 5
    tRAS: 15
    tRC: 20

    Wouldn't this work or is there a risk of damaging the mb/ram?
  9. antimatter86 said:
    lol thanks Darth, I wouldn't want to damage the mb/cpu

    The newer RAM i believe is cheaper.. like $25, so I guess I could get 2 more of the new ones and replace the older RAM instead, right? Although, I will be pissed if it still reads 6 gigs usable, or even lowers the value, because of some weird comparability issue with the newer RAM and the older mb.

    Well thats depend of how old your MB is and what CAS latency RAMs it is made to handle. Normally you cant put in other types than those that existed when buying your old PC components :non:

    If you can get new 5.0 RAMs it may works but before doing so you just have to be convinced that this is going to work. Look in the manual and see what kinds of RAM your MB is thought to handle. Keep on searching those forums and read everything you can, then go to a PC store you can trust (thus the golden rule is NEVER trust anybody in the PC market...) and ask them about this. If they in 5 minutes say "this will work if you buy those new memorys, I have done this myself at home" :heink: :non: - run away as far you can and choose another PC store!!! When and if you got any answers from the "experts" come back here later and tell us about it all in this thread of yours!

    Good luck and don´t give in :sol:
  10. What channel configuration are you running the RAM in.

    If the DIMM's aren't installed in the right or the channel configuration is wrong, it could be preventing the BIOS from detecting all the RAM correctly.

    Also, if you do adjust the latencies, you need to set them all to the higher numbers. (Higher is worse/slower for latency)

    I'm assuming that your old and new RAM are both DDR2 Ram. If they are different, it will not work at all.
  11. Hm... what do you mean in by "the right (slot)" , their's only 4 slots and their were only two open slots available for new RAM.

    How do you check channel configuration for RAM? Not sure what that even is.
  12. Best answer
    First, move the modules so your original RAM is in slots A1 and A2 (first set of yellow/black) and the new RAM in slots B1 and B2 (second set of yellow/black). Based on your CPUZ figures it appears that you had your RAM staggered (filling both yellow slots).
    Try that and see if it changes anything.

    If that doesn't work, here is some RAM that more closely matches what was in your system and is guaranteed compatible. It is a different speed than what you have now so as I recall it will run at the same speed as your original RAM
  13. i recommend updating your bios if its not the latest bios... it may solve your problem without having to return/replace/buy new ram... but as stated above make sure your rams are in the correct slots.
  14. Best answer selected by antimatter86.
  15. Getting a solid state fixed this. Aint that some weird ..stuffs.

    All 8 gigs are being used now and lag free so far. :)
  16. Good for u!
  17. This topic has been closed by Nikorr
Ask a new question

Read More

Asus RAM Motherboards