Nvidia 780i motherboard - slots 1&3 fried?

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Thread: Nvidia 780i motherboard - slots 1&3 fried?

  1. #1
    Sushi
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    Nvidia 780i motherboard - slots 1&3 fried?

    Hi all,

    My system (nvidia 780i SLI motherboard, all 4 DIMMS filled with 2GB Mushkin PC2-6400) was running fine for 2.5 years, until yesterday when it shut down. On reboot, I was getting C1 errors, suggesting something about the memory was no longer happy.

    From the CPU side, this motherboard identifies its DIMM slots as 0 and 2, then 1 and 3. Running Memtest, I learned:

    1. Individually, all 4 memory sticks successfully pass memtest in slots 0 or 2.

    2. Individually, they each fail in slots 1 or 3.

    3. I can put 2 sticks into slots 0 and 2 and pass, but because that's not the correct matching slot pair, the system thinks only 2 gigs are on board. Matching pairs are 0 and 1, 2 and 3.

    4. Adding a third or fourth stick into 1 and/or 3, and I'm getting the C1 error again.

    After, I tweaked the memory voltage up a bit, from 1.8 to 1.95v, even upping the north bridge to 1.4v. And tuned down the timing to 5/5/5/18/2T. No change, switched it back to defaults.

    So, all 4 sticks seem fine, but slots 1 and 3 (the two furthest from the cpu) are suddenly unhappy. Bad memory controller on the motherboard, then? Is there anything I can do to revive it?

    And even if not, is there a way I can get the mobo to recognize both 2 gig sticks sitting in non-paired slots 0 and 2?

    Thanks for any help. Cheers.

  2. #2
    Mako Shark wh666-666's Avatar
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    Sounds like you've thoroughly tested and ruled out possibilities like faulty sticks, certainly seems like the dimms.

    Can you see any bulging or rusted caps on the capacitors on the board? If so, they might need replacing.

    So it is either new mobo time, or you can try a last ditch repair. I've rescued quite a few that were thought of as dead using the oven trick:

    - Strip off all parts like the CPU
    - Strip off all mobo heatsinks like the northbridge
    - Lay flat on a preheated large baking tray, cook at about 190*c for 3mins-4mins
    - Take baking tray out, leave on side to cool for 20 mins or longer, till its cold.
    - Attach all heatsinks (remember paste), build PC back up and boot.

    Ive rescued a few motherboards from death with this. Sometimes the repair is permanent, sometimes only works temporarily. By placing it in the oven, it is supposed to remelt solder on connections.
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  3. #3
    Great White Shark
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    Another thing is that something inside the memory controller has given up the ghost. Keep in mind that running 4-DIMM's is much more stressful on the memory controller vs. 2 DIMM's.

    This is one of the reasons that 2-DIMM's can often run at 1T timings, but 4-DIMM's will require dialing back to 2T timings.

    What are the stock timings on your RAM as reported by the DIMM's SPD entries?

    *Edit: Just looked up the essentials kit, it is as you said 5-5-5-18 2T @ 1.8V

    *Edit2: Noticed you never mentioned if you were able to get 2 DIMM's running in slots 0/1 (I.e. dual-channel mode, interleaved or not) Is this functional?
    Last edited by James; 01-27-2012 at 01:43 PM.

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  4. #4
    Sushi
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    Thanks for the replies.

    I don't see anything obviously out of place on the motherboard. The system had been running stably for years, and then this happened out of the blue.

    And no, a DIMM in either slots 1 or 3 (with or without a DIMM in slots 0 and 2) prevents the system from booting. So, no dual channel.

    I'm going on the opinion that, for whatever reason, the second memory controller has died. I'll see if the board is still under warranty (maybe create a file server out of this rig), and begin speccing up something new.

    Thanks again,

    M.

  5. #5
    Mako Shark wh666-666's Avatar
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    I doubt it would be under warranty after all this time. If it isn't, rather than chucking it, try repairing it.
    Compaq A910em: T2330 dual core 1.6Ghz, X3100 384MB GPU, 160GB sata HDD, 2GB RAM
    Gaming rig: Asus Striker II, Coolermaster GX 750w, E4600 @ 2.4Ghz, 2.5GB RAM, Zerotherm FZ 120, 9500GT 1GB
    Server: Mac mini running W23k Server - 1.8Ghz dual-core, 1GB RAM, 1x80GB, 2x500GB externals + LTO1 tape backup

    An important petition, regarding your human rights:
    https://www.change.org/en-GB/petitio...r-both-genders

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