P9X79-E WS + F3-19200CL10Q2-64GBZHD = Strangness

[murdaugh]

System
New P9X79-E WS
New 4930K
ANtec 1200W psu
F3-19200CL10Q2-64GBZHD (Used previously with a p9x79 ws and a 3930k with no issues).

Symptoms.
When Set to auto mode the ram runs as 1333 as expected. All 64gigs show up. Intel Burn test does multiple passes with no problems.

When set to XMP Profile 1 (or 2) ram is now at 2400 but only 40gigs shows up in the bios and in windows. Intel Burn test does multiple passes with no problems. Aida64 Shows all 8 sticks of ram present. CPUZ also shows all 8 sticks present.

When set to Manual 2133 9-11-11-31 only 60gigs shows up (instead of 64gigs) in the bios and in windows. Intel Burn test does multiple passes with no problems. Aida64 Shows all 8 sticks of ram present. CPUZ also shows all 8 sticks present.

This is all at stock speeds and default settings throughout the bios with the newest bios installed.
Also sometimes at 2400 it will show up in Aida64 as being in dual channel or tri channel mode instead of quad channel. GPS in intel burn test are lower when the mode is not showing quad channel.

Tried using the mem ok button to try to make it relearn the ram but had no effect.

When I remove half the sticks all is normal at 32gigs. runs 2400 at stock cpu speed and even with the cpu running at 4600.

When I add 2 more sticks. it tops out at 40 gigs again when at 2400 (should be 48gigs).

When the ram is put back into the P9X79 WS with the 3930k all is still well there.

Does this sound like the motherboard needs to be rma'd?

[HiVizMan]

The IMC is on the CPU as you know, and it sounds as if your first CPU has a very good IMC. The board should not make too much difference at all with regard to memory being picked up.

But let us test each slot using Memtest86+ and see if the board is defective. Basically test each slot and then see which combination of slots do not get picked up when populated.

[Raja]

I suspect it's not the DRAM or the board that's faulty here but the IMC not being able to run DDR3-2400. The IMC will drop any DIMMs/ranks that are not stable during POST. Not many CPUs can run DDR3-2400 unconditionally stable - and often those that can need manual adjustments. The fact that the DIMMs all map at stock, and then fall off as you increase DRAM frequency, leads me to believe this is more an IMC/memory timing issue.


Depending upon how good that IMC is, you may need to manually change the following (no guarantees this will fix it however):

1) VCCSA may need to be increased - some CPUs need it to be over 1.30V with 64GB of memory at DDR3-2400.

2) Some of the memory sub-timings may need relaxing. I can help you with that if you post images of the DRAM timing pages. You can save screenshots with a FAT32 formatted flash drive and by pressing F12 in UEFI. Convert them to JPEG and upload them so we can see them.

3) DDR3-2400 might simply not be a good idea on that CPU if too many timings need to be relaxed in order to achieve it. In such case, running at a lower frequency with tighter timings is actually faster. We can advise you on that too.

Users often fall prey to thinking XMP at any frequency and density is a given to work plug-and-play. Things don't work that way unfortunatley - even on top dollar memory kits. The CPU plays huge a part in the equation and to an extent the board, too.


As a "by the way": it gets harder to keep memory freqeuncy high as the CPU core frequency is overclocked, too...

-Raja

[murdaugh]

I had never seen this behavior before so it threw me. I found a setting to ignore the memory training errors and then I got the behavior I would have expected when the IMC cant handle the speed. All 64gigs showed up but lots of errors.

I then put that setting back to auto, and swapped the cpu out with a 4960x that is going into my RIVBE when it gets here tomorrow. This cpu posts with 61gigs and quad channel active. I will be pairing this CPU up the the 2400 memory in the RIVBE so I will wait until it is up to see what tuning needs to be done on that one.

I will be putting a set of 2133 Ripjaw Z F3-2133C9Q2-64GZH into the P9X79-E WS along with the 4930k tomorrow.

This is actually a very nice feature (having banks with problems dropped out during post). System has been completely stable through all these tests. My p9X79 WS and RIVE never acted like this when I was overclocking with the 2400 memory.

[Raja]

This is something that has become prevalent on Ivy-E (dropping DIMMs and ranks). SNB-E was not as prone to it.

[murdaugh]

Your diagnoses has been confirmed. I put the 3930k in the p9X79-E ws and put in the same bios settings I used on the old P9X79 WS and every thing worked great.

I RMA'd the 4930k since it could not see 64gigs at anything over 1333 speeds.

The 4960x worked great in the -E WS at 2133 while clocked at 4.6 which is the same overclock I used with the 3930k.

This is now resolved... Thanks for the help

[HiVizMan]

All good I am pleased you are sorted.