64GB of RAM in PC at default speeds, 2 modules disappear when XMP is enabled.

[lilshaney]

Hi guys,

 

I have just bought some more RAM, I have 64GB of DDR4 CORSAIR VENGEANCE 2400MHZ 6 of 8 DIMMS are identical but the other two are still the same but the last number in the timings are different to the rest of the RAM. This wasn't an issue before as it clocked to the recommend speed of 2400MHZ when I had only 32GB. Now with 64GB of RAM all show up without XMP but when I enable XMP only 48GB shows up. I have an Asus x99-s and and i7 5930k with 750w psu and gtx 1080ti

 

Thanks!

[Windows7ge]

You can try setting the speed/timing/voltage manually. Set it to match the XMP profile of the 2 modules with higher timings. The rest of the ram should respond fine to this and performance wise you shouldn't see any significant impact.

[lilshaney]

@Windows7ge How do I change these timings to 2 dimms are 14-16-16-31 The other 6 are 16-16-16-39 which do j change too?

[lilshaney]

Okay, I've tried both timings manually and both times 2x dimms disappear and it's not even the dimms with the different timings it is d1 and d2 on my x99-s is this a cpu limitation?

[lilshaney]

Just now, lilshaney said:

Okay, I've tried both timings manually and both times 2x dimms disappear and it's not even the dimms with the different timings it is d1 and d2 on my x99-s is this a cpu limitation?

All ram shows without any kind of oc

[done12many2]

2 hours ago, lilshaney said:

Hi guys,

 

I have just bought some more RAM, I have 64GB of DDR4 CORSAIR VENGEANCE 2400MHZ 6 of 8 DIMMS are identical but the other two are still the same but the last number in the timings are different to the rest of the RAM. This wasn't an issue before as it clocked to the recommend speed of 2400MHZ when I had only 32GB. Now with 64GB of RAM all show up without XMP but when I enable XMP only 48GB shows up. I have an Asus x99-s and and i7 5930k with 750w psu and gtx 1080ti

 

Thanks!

 

You don't want to mix RAM with x99 unless you know how to manually set timings.  The IMC on Haswell-E and Broadwell-E can be picky due to quad channel.  

 

With that said, you can still get them to work.  You're just going to need to figure out which combination makes it happen.  

[lilshaney]

It is now fixed I just put the RAM in one stick at a time and made sure XMP was still enabled, everything eventually worked perfectly. Very weird issue indeed. But the main thing is all the RAM works fine with XMP even though 2 DIMMS are mis-matched and the best part is even quad channel works!