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AsRock P55 Extreme/8GB RAM: COLD boots find only 4GB, 2 modules

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  • AsRock P55 Extreme/8GB RAM: COLD boots find only 4GB, 2 modules

    Hi all,
    I've recently bought an AsRock P55 Extreme, fully populated with 4x2GB modules RAM Corsair 1600 MHz cas 9, running at the safe value of 1333 MHz, 9-9-9-24. I've installed a Core i7 860 cpu on it and I do not overclock.
    At cold boots the motherboard does recognize only 2 modules, 4GB total. At hot boots it finds all modules, 8GB total.

    This is what happens:

    Case A)
    I power on the psu and boot the pc. At cold boot the motherboard only sees 4GB and that's put on screen, it reads 4088MB:

    I let the boot continue and, when in windows 7, I can read:

    and in Linux I find that situation:

    From the POST to the OS login the memory used is 4GB.

    Case B)
    The very moment I read 4088MB on POST during the cold boot I press Ctrl+Alt+Canc and let the system reboot. Now the pc performs a hot boot and the memory is correctly recognized, the POST reads 8184MB:

    windows 7 and cpu-z read:

    and Linux too uses all 8GB ram:

    Now let's try an intermediate step in Case A).
    After the POST reads 4088MB I press F2 and enter the BIOS setup utility where I can see (with amazement, I admit...), a system summary where all 4 slots are correctly indicated as populated, the total amount of memory is 8GB and it can determine the DRAM frequency too:

    I flashed my bios with almost every official bios version from AsRock, from 1.60 to the 2.70 one, with no improvements at all. I tried configuring the bios, specially the dram timings, with no effect: at every cold boot the system only manages to find 2 modules/4GB and I need everytime to reboot in order to let it sees all of 8GB.

    As suggested by AsRock Support I performed a list of test:

    - I disassembled and reassembled the whole system, from cpu to memory;
    - I tested every single ram module with memtest+ and they all passed it;
    - I switched ram modules and dimm slots with every possible combination;

    everything goes nowhere, the cold boot can't see 4 modules, the hot boot does.

    What do you suggest guys?
    Thank you for reading and sorry for the long post ;)
    Last edited by hosh; 09-14-2010, 06:24 PM.