Z6 G4 2nd CPU RAM issues

[Byhtomit]

So, as an HP partner, I have a customer that is experiencing this ***problem. They have four 8GB memory modules, with two modules paired to each CPU. I have swapped the memory from one CPU to the other CPU, but the system still only sees 16GB of memory instead of the full 32GB. However, the second CPU is seen as expected, just the memory associated with that CPU is absent. The BIOS has been updated to the latest version (2.21 dated 6/28/2019) and I have swapped out the riser card thinking that a faulty card was preventing the memory from being seen. This did NOT solve the problem. I loaded the BIOS factory defaults to hopefully reset what is wrong, but the same problem still exists. Both CPUs are seen, but only the memory attached to CPU0 is available, which is verified in the BIOS as well as HP's 4-in-1 diagnostic tool. I'm going to keep searching the internet to see if anyone else has seen and solved this issue, but it would be helpful if someone from HP would chime in here. Thanks, Timothy

edited***

[BambiBoomZ]

Byhtomit,

I'm not an expert in memory problems, but here are a couple of ideas to help narrow the possibilities:

As the 2nd CPU riser board was changed and the problem persists,:

1.  The riser and second CPU were added to the system later and the M/B RAM is unbufferered.  Change to HP tested, registered RAM throughout. Ensure that all module match as the speed and timings need to be able to sync.

Dual CPU systems seem to be a bit quirky if the the memory configurations are not symmetrical.

2.  As it requires 4 modules to complete one memory channel, consider borrowing four more modules and complete one memory channel for each CPU.  I'm not certain of this as all my dual CPU systems (Precision T5400, T5500, HP z620) have had a complete and matching capacity memory channel for both CPU's.

3.  Verify that the placement of the modules is correct as to the memory channels.  The modules need to be on the same channel for both CPU's

4. The memory controller on the 2nd CPU is bad at least on one channel.  To verify, swap CPU0 and CPU1.

I hope others more expert in memory matters will comment.

BambiBoomZ

HP z620_2 (2017) (R7) > Xeon E5-1680 v2 (8-core@ 4.3GHz) / z420 Liquid Cooling / 64GB DDR3-1866 ECC Reg / Quadro P2000 5GB _ GTX 1070 Ti 8GB / HP Z Turbo Drive M.2 256GB AHCI + Samsung 970 EVO M.2 NVMe 500GB + HGST 7K6000 4TB / Focusrite Scarlett 2i4 sound interface + 2X Mackie MR824 / 825W PSU /> HP OEM Windows 7 Prof.’l 64-bit > 2X Dell Ultrasharp U2715H (2560 X 1440)

[ Passmark Rating = 6280 / CPU rating = 17178 / 2D = 819 / 3D= 12629 / Mem = 3002 / Disk = 13751 / Single Thread Mark = 2368 [10.23.18]

HP z420_3: (2015) (R11) Xeon E5-1650 v2 (6C@ 4.3GHz) / z420 Liquid cooling / 64GB (8X 8GB DDR3-1866 ECC registered / NVIDIA GeForce GTX 1060 6GB/ Samsung 860 EVO 500GB + HGST 4TB / ASUS Essence STX / Logitech z2300 2.1 / 600W PSU > Windows 7 Professional 64-bit (HP OEM ) > Samsung 40" 4K

[Passmark System Rating: = 5644 / CPU = 15293 / 2D = 847 / 3D = 10952 / Mem = 2993 Disk = 4858 /Single Thread Mark = 2384 [6.27.19]

[DGroves]

you might try re-seating the cpu and inspecting the socket pins on the socket that has the memory issue

i had a z820 that would see all banks when filled with 2 or 4 gb dimms for both cpu's but the sec cpu bank would not see some of the 8gb modules this was traced to bad contact between the cpu and the socket pins