Single channel memory works but not dual channel memory

I am having a strange erratic memory problem.

If I put a kingston value ram 1333Mhz in slot 1 and boot into memtest86+ ver 4.2 it passes.
If I add the same type of memory to slot2 (slots 1,2 form a dual channel) the memory test fails.

I have test both memories individually in slot 1 or 2 or 3 or 4 and they all pass. I have used bios failsafe settings and under clocked it to 800Mhz.
None of that makes any difference.

I have exactly the same problem with slots 3,4. Memtest86 will fail if both slots are filled but passes when only one slot (any slot) is filled.

Machine specs
AMD Phenom II X 6 1090T processor
msi motherboard with amd 890GX chipset. Bios updated.
kingston value ram DDR3 1333Mhz 2G DIMM x4 (bought as a single pack)
video card is internal radeon hd 4290 or nvidia gtx 560ti (makes no difference)
all disk drives are disconnected as I boot off a memory stick.

Is this problem a motherboard or memory controller (integrated in cpu) problem?

Thanks any help or suggestions would be helpful.
6 answers Last reply Best Answer
More about single channel memory works dual channel memory
  1. Best answer
    I would say there is something different enough about the RAM sticks that they can't stripe properly in a dual channel set. The motherboard is supposed to detect this and disable dual channel mode, but something is not working.

    It could be a memory controller issue (doubtful) but you'd have to try some different RAM in dual channel mode to isolate that.
  2. 800 speed is the wrong speed for ram dimm. with one dimm use cpu-z amd under memory tab look at the spd info. look at the timing and speed for the ram. 1333 ram runs at 1/2 speed. so a 1600 ram is 800 speed. 677 is the speed or a number near that number for the ram. then the timmig should be set as 9-9-9-9-9 or 10x depending on the memory spec of the ram. also make sure your mb bios is up to date for cpu and ram code.
  3. download ubuntu and make bootable cd boot from cd then test ram by using the option given in cd. i think u r software in pendrive is a corrupted file so come this try in cd.
  4. Before test ram load default settings in bios.check if the cmos battery has power or its dead.try changing cmos battery.
  5. SOLVED:
    Thanks for all the replies. I stripped my computer cleaned all the dust from memory slots, cpu slot etc. I bought one new kingston memory (I lost patience, I have been testing for a week) replaced the suspect and now my computer passes the memory tests will all 4 DIMMs in all 4 memory slots, 8Gigs of ram, slots 1,2 dual channel, slots 3,4 dual channel mode.

    Interestingly the memory stick I replaced does work on its own but not with the other ones. Maybe the cleaning also helped.

    Thanks for all your help
  6. Best answer selected by robbo54321.
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