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Old 10-19-2009, 07:14 AM
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Default Troubleshooting Thread for Incorrect Memory Amounts on X58 and P55/H55/H57 Platforms

World renowned RAM connoisseur EVA2000 has assembled a short and effective troubleshooting guide for users with issues running 6 up or 12GB on X58 motherboards. He initially compiled this for the ASUS boards but, the fundamentals apply to all X58 boards although the terminology for some settings may vary from board to board.

Please look this over if you are having issues. If you have a forum thread or start a TSX EXPRESS CASE, please tell us if you have tried these steps:

Quote:
Originally Posted by eva2000 View Post
Across various forums, folks reporting sometimes that they detect less memory available in windows, bios, memtest86+/DOS, that physically installed. For example, installed 6GB or 12GB and only detecting 4GB or 8-10GB respectively.

I thought I'd outline some possible reasons for detecting less memory than installed:
  1. incorrect cpu vtt (uncore) voltage set - what Asus terms as QPI/DRAM voltage
  2. incorrect QPI/DRAM to VDIMM relationship - every cpu/mem pairing will have an optimal voltage differential between QPI/DRAM to VDIMM voltage usually between 0.01 to 0.5v difference. Fall out of the optimal differential voltage for cpu/mem pairing will = less memory detected and/or lower memory bandwidth reported compared to when optimal voltage differential is in place.
    • Example, say you have 6x2GB @1333mhz working fine at 1.35v QPI/DRAM with 1.65v VDIMM. You try to overclock the memory to @1600mhz speeds, and you bump VDIMM from 1.65v to 1.75v and now only see 8-10GB detected. You've moved out of the optimal differential range for QPI/DRAM to VDIMM which @1333mhz was 1.65 - 1.35v = 0.3v. At 1.75v VDIMM you left QPI/DRAM at 1.35v so 0.4v differential voltage. Then you bump QPI/DRAM to 1.45v to keep 0.3v differential voltage and 12GB is detected again. Now this is just an example, it could be you need 1.85v VDIMM for your memory to be stable and if 0.3v is optimal differential voltage it means you need QPI/DRAM set at 1.55v
  3. faulty memory modules
  4. faulty memory dimm slots
  5. sort of combination of 3+4 above where memory modules like particular memory dimm slots - could come down to PCB differences for each module along with voltages for QPI/DRAM and VDIMM.

Also don't count out needing to tweak, IOH, IOH/ICH PCI-E, ICH voltages as well as DRAM DATA/CTRL REF voltage tweaks for each memory Channel A/B/C

When testing full memory dimm slot populated configurations, it's also worth testing each memory module (label them with masking tape from #1 to #6) in each of the 6 dimm slots, jot down notes as to how each module performs in each of the 6 dimm slots, then pair them up with best matching of memory modules for dimm slots. Reason is triple channel kits while sold to you as matched, they are rarely really matched in terms of overclocking characteristics - you'll always have a module or two which either does better or worse than the average of the 3 modules. Now take that to 6 modules and you can see why sometimes it might not work that well.

HTH

George
Here's the original thread for those that are interested: http://i4memory.com/f54/asus-x58-6-1...00/#post121626

Also, be sure to inspect your CPU cooler mount. Over tightening or unequal pressure on the CPU socket can cause the CPU to not seat correctly. Frequently, this translates into what appears to be memory related problems because the CPU/IMC is not making proper contact with the pins leading to the memory sockets. The fundamentals here apply to systems with 3 modules also and especially when overclocking. This applies to P55/H55/H57 also. In any situation where you have these issues and where the above steps do not work, please remove your CPU and inspect the socket for bent pins
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Last edited by Yellowbeard; 02-23-2010 at 05:31 PM.


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