Hey guys,
 
A couple theoretical and practical questions here.
 
Motherboard: X58 SLI - 132-BL-E758-TR
CPU: i7-920 @ 3.0 GHz (mild overclock)
OS: Windows 7 64bit Professional OEM
 
I have been running 12GB of ram (6x 2GB dimms, trichannel 1600)  and saw all the low prices on 8GB kits (2x 4GB) at Newegg, so got three of them and thought I'd try and see if I could get my X58 to run them. (Check Newegg for F3-10666CL9D-8GBRL, it's DDR3 1333 at 9-9-9-24-2N).
 

• I throw the new ram in and boot up and head over to System info and it says "Installed ram: 24GB (16GB usable)"
• I start up memtest which lists only 16GB of ram installed, and indicates it is running in dual channel mode, although it indicates all six memory slots are filled with "4096 MB PC3-10600 - G Skill Intl F3-10666CL9-4GBRL"
• I check my BIOS and I have the following settings:
  • Memory Control Setting - Enabled
  • Memory Frequency: Auto (Target: 1202Mhz)
  • Channel Interleave Setting: 6 way
  • Rank Interleave Setting: 4 way
  • Memory Low Gap: Auto

SO... my questions:

• Is my motherboard capable of accepting dual-channel ram and running it as tri-channel?
• If so, why are only 16GB of the 24GB usable, when both memtest and the OS "see" all 24GB
• And lastly, what is the "how" in this case?

Here are some of my next steps, let me know if I need to add to the list:

• Play with ram positions--pull out 3, see if it recognizes 12GB, replace those with the other three, ensure it also sees the 12GB, put all six back in (note: it recognized and used all six of the 2GB dimms I was using previously, so I think I can rule out a bad ram slot)
• Return the BLCK to 133 from 149
• Check my BIOS version and see if there is an update (admittedly, I am unsure which BIOS version I am running, and I bought the mobo in March 2009)

 
Thoughts?

Disregard, I reread you post sorry

I bought two sets of dual channel white Corsair vengeance LP 1.35 volt DDR3 ram and I am using three out of the four DIMMs running 12GB very stable.

Posting screengrabs from my BIOS. I upgraded to the latest BIOS off the EVGA website and upped the VTT and DIMM voltage a bit, but it's still only registering 16 of the 24GB. I also removed the overclock and took the BLCK to 133 from 150 (2.8 GHz with turbo mode). What's a good next step?
 

Checking for bent pins in the CPU heatsink, remounting the cooler. Also what OS are you using?
http://msdn.microsoft.com...emory_limits_windows_7
Windows 7 Home Premium has a limit of 16 GB

tagging along.......