four sticks, no xmp cpu's fault?

[john terragon]

Hi.
I've got a 5950x and 4 sticks of DDR4 with 3600 xmp frequency. If I install two of them at a time then I can use the xmp profile and memtest86 gives zero errors. If I install all of them then memtest86 gives errors at 3600. But all four at 2666 are fine with memtest86.
I think I've read somewhere than when this happen the culprit is the memory controller on the cpu.
Is that right?
If that's the case then it would be useless to try to change the 4 dimms. Any 4 dimms of any model would give the same problems at 3600 right?

Also, the tests have been conducted with pbo enabled (nothing crazy, just the standard settings). Is pbo causing this? You know, like in certain intel cpus that when you overclocked them you lost the possibility of overclocking the RAM too?

Thanks

 

[john terragon]

32 gb each

 

[john terragon]

OK. I'll try it.
To find the maximum working frequency can I just keep the timings from the 3600 xmp profile and then lower the frequency until I get no errors? (and maybe later, when I have a max frequency, tight up the timings?).

 

[john terragon]

yea, thats exactly how you should go for it
2T command rate may be necessary for 4x dual rank sticks, altho so far 1T and GDM on has always worked for me

Those are all greek to me but I'll look them up.
Things look volatile though because at 3200 memtest86 started to show errors after 50% while on 3000 it failed almost immediately.

 

[john terragon]

The problem is trying to run 4 dual rank sticks at high speeds on X570 doesn't work well. The memory controller and the board have an impact on the max speed possible.

Yes.
However I have another 5950x on a very similar board, msi ace x570, and in that case another 128gb 4 sticks, this time with 3200 xmp, work wihtout a hitch.
So, maybe I've been unlucky with the second 5950x and the msi ace x570s max, which actually should be better with memory than the old msi ace. So maybe the culprit is the new 5950x.

 

[john terragon]

Just to close the topic.
I've changed the four sticks of DDR4:
before: patriot 128GB 3600 Mhz 18 22 22 42
now: kingston 128GB 3600 Mhz 18 22 22 39

Before the only stable frequency was 2666
Now, with the new ones it's rock solid at 3600 without changing anything from the xmp profile.

So we have two cases:

1) If the culprit for the instability was the cpu+mb because 128GB dual rank at 3600 was asking too much of them then I don't understand why now with the same speed and size cpu+mb are suddenly able to handle them.

2) On the other hand, if the culprit was the first kit of memory then I don't understand how ca nthey work at 3600 one pair at a time but then they become unstable when all four are installed (having excluded that cpu+mb can't handle them).

It's a mistery to me.