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GA-X99-Phoenix-Sli; Rev1.0, Fails to detect one of two 32GB RAM

Hi Team,

I have purchased a GA-X99-Phoenix-SLI Motherboard to built my own server. Specification given below

Motherboard:   GA-X99-Phoenix-SLI; Rev1.0
CPU : Intel® Xeon(R) CPU E5-1620 v4 @ 3.50GHz × 8
RAM: Skhynix, 2x32GB, 2Rx4, DDR4, 2400MHz Registered , Unbuffered Memory modules
Heat Sink: Cooler Master - Fan cooled heat sink
SMPS: Seasonic, 750watts, 100-240VAC
Hard Disk: 1TB, WD internal hard-disk drive
DVD-ROM: Samsung DVD Drive
OS : Tried different Operating Systems - Linuxmint 18.0, Windows10 Pro, Currently running on : RHEL 7.5

# the ram modules were installed as per motherboard suggestion on DIMM slot 1B and 1C (Total of 8 DIMM Slots available)
# When booted, the Bios was able to detect both ram modules and booted onto the OS.
# After running for 30 mins, the system hung for a while and rebooted
# While  rebooting the motherboard bios detected only one ram module (32GB - Say R1) and R2 was not detected.
# The Easy setup in BIOS shows ram  modules in both DIMM slots, but shows installed memory as only 32GB.

Steps taken to fix the issue:
1. Reboot the System few times, no success.
2. Took away R1 and R2, Installed only R1 in slot 1B, booted the system, R1 detected by both BIOS and OS
3. Tried the same ram in other Slots 1A,  1C and 1D - In all cases, the bios and OS detected the module.
4. Took away the ram R1 and installed the second ram R2 in slot 1B, booted the system, it was detected by both bios and OS
5. Now installed the ram R1 in Slot 1C and R2 in Slot 1B - but this time only R1 was detected and R2 was shown present in Slot 1B, but installed capacity shows 32 GB only.
6. Tried ram R1 and R2 in different combination of slots ( like, 1A & 1B, 1A  and 1C, 1A and 1D, 1C and 1D) but no luck.
7. So I thought that ram R2 maybe bad and got it Replaced with RMA.

But, after installing both R1 and new ram R2 , Bios easy setup is showing both memory module is present, but installed memory as 32GB. its not  showing the fully installed memory 64GB.

Again i tried below troubleshooting steps
1. Used only ram R1 in Slot 1A and bios EasySetup shows the presence of R1 and installed memory 32GB and the OS also detected it.
2. Used R1 in Slot 1B, and was detected by both bios and OS.
3. When used in Slot 1C and 1D, R1 was detected by both bios and OS
4. Tried the above three steps for new ram R2 only , without ram R1 and new ram R2 was detected in all instance by bios and OS.
5. When I installed the ram R1 and new ram R2, bios detected both rams  and showed installed capacity as 64GB. The OS also detected both rams and showed the installed ram as 64GB. After running for 30 minutes, the system crashed or maybe rebooted and after that the bios and RAM detected only R1.
6. Took ram R2 and cleaned it and installed it back. After that both rams were detected by bios and OS, the system ran for around 20 minutes, but then crashed  and  booted again, but  detected ram R1 only.   
7.  Tried ram R1 and new ram R2 in different combination of slots ( like, 1A & 1B, 1A  and 1C, 1A and 1D, 1C and 1D) but no luck. only R1 was detected.
8. When using  only either R1 or R2, the bios detects the 32GB and system runs without issue
9. When both rams are used in dual channel mode, system runs only for around 20 minutes detecting 64GB, then reboots and detects only R1.
10. Tested both R1 and R2 individually with memtest86 , with all CPU active simultaneously and the test ran all pass without errors,
11. Tested both R1 and R2 individually with memtest86, with all CPU active simultaneously and the test indicated error (forgot the error type reported)
12. When i clean the rams R1 and R2, both rams were detected by bios and OS, but runs only for a short time and then reboots detecting only R1

I see both R1 and R2 are working good as when they are used individually. But together they  do not work .
I tried reseating the CPU and re-installing the heat-sink with just only screw  tight, still no luck.
I also tried updating the Bios from primitive version to the last but one of the latest versions which is for enhanced memory compatibility, but still no luck.

Any suggestion to find the root cause of the issue and help to fix it will be  much appreciated and it would be a great help.

Regards
Elango
« Last Edit: August 30, 2018, 06:59:29 pm by Elango Ganesamurthy »